FOR PUBLICATION
 UNITED STATES COURT OF APPEALS
      FOR THE NINTH CIRCUIT

UNITED STATES OF AMERICA,                  No. 06-30215
                Plaintiff-Appellee,
               v.                            D.C. No.
                                          CR-05-00193-BLW
SONNY SNIPE,
                                              OPINION
             Defendant-Appellant.
                                      
       Appeal from the United States District Court
                 for the District of Idaho
        B. Lynn Winmill, District Judge, Presiding

                  Argued and Submitted
            February 7, 2007—Portland, Oregon

                  Filed January 28, 2008

   Before: David R. Thompson, Andrew J. Kleinfeld, and
               Jay S. Bybee, Circuit Judges.

                 Opinion by Judge Bybee




                           1309
1312                   UNITED STATES v. SNIPE


                             COUNSEL

David N. Parmenter, Esq., Blackfoot, Idaho, for the
defendant-appellant.

Michelle Mallard, Assistant United States Attorney, United
States Attorney for the District of Idaho, Pocatello, Idaho, for
the plaintiff-appellee.


                              OPINION

BYBEE, Circuit Judge:

  Appellant Sonny Snipe1 challenges his conviction and sen-




  1
    Appellant’s surname is spelled inconsistently throughout the record.
We refer to Appellant as Snipe, pursuant to the Presentence Report, which
states: “The defendant’s true name is Sonny Ray Snipe, not Snipes as
listed in the indictment.”
                       UNITED STATES v. SNIPE                      1313
tence for possession of a firearm with an obliterated serial
number in violation of 18 U.S.C. § 922(k) and 18 U.S.C.
§ 924(a)(1)(B). Snipe’s conviction followed a warrantless
entry by police, who were responding to an emergency call.
During the course of their search, police saw drugs in plain
view. They returned with a search warrant and seized drugs
and the firearm. Our review of Snipe’s motion for suppression
requires us to revisit, and modify, our decision in United
States v. Morales Cervantes, 

, 888 (9th Cir.
2000), in light of the Supreme Court’s recent decision in Brig-
ham City v. Stuart, 

(2006). For the reasons set
forth below, we affirm.

                                    I

   At approximately 5 A.M. on January 1, 2005, an unidenti-
fied “very hysterical sounding” male called the Fort Hall
Police Department. The caller screamed something to the
effect of “[g]et the cops here now” or “[g]et the cops now” to
the residence of Dennis Snipe, Sonny’s father. The call was
then disconnected. The police dispatcher contacted two offi-
cers on a secure emergency frequency and instructed them to
report to the Snipe residence. Activating their emergency
lights, Officers Jesse Rodriguez and Mark Massey responded
separately to the dispatch. Arriving at the residence,
Rodriguez—who lived down the street—noticed a vehicle
that he did not recognize parked in front of the house and an
individual that he also did not recognize “walking into the res-
idence.” Id.2 Both officers also noted that—unlike the other
homes in the area—the residence’s lights were on.

  Rodriguez and Massey proceeded to the residence and
noted that the door was partially ajar. Rodriguez then knocked
  2
    In his suppression hearing testimony, Massey recalled that after he
arrived on the scene, he met briefly with Rodriguez who told him that “he
[had] observed somebody running into the house as he pulled in.” (empha-
sis added).
1314                 UNITED STATES v. SNIPE
on the door and announced “Fort Hall Police Department.”
The force apparently knocked the door open, and both officers
stepped inside. Upon entering, Rodriguez noticed an individ-
ual sitting on the couch that he did not recognize and—
apparently a split second later—noticed several other individ-
uals seated around a kitchen table, including Snipe. The indi-
viduals at the table reacted with surprise to the officers’
arrival and asked why they were there. Rodriguez then asked
who was hurt and stated that the police “had received a call
[from] a hysterical male” asking the police to come to the res-
idence. As Rodriguez spoke, both officers noticed “what
looked like . . . a large amount of drugs” sitting on the kitchen
table, but neither officer mentioned or questioned the individ-
uals about the drugs because the officers “were mainly con-
cerned if there was someone hurt inside the residence.”

   After denying anyone was hurt, Snipe told Massey “to go
ahead and look around” and upon Rodriguez’s suggestion,
Massey proceeded to look through the residence. Massey
checked the entire residence, except for a locked bedroom;
when Massey asked Snipe why the room was locked, Snipe
responded that the room was his father’s and he did not have
a key. Snipe told Massey, however, that he could “[j]ust kick
it in” if he needed to search that room too. Massey declined
to kick in the door. After determining that there was no emer-
gency, the officers left the house and promptly obtained a
search warrant based on their observation of illegal drugs on
the kitchen table. During a subsequent search, the officers dis-
covered more drugs, drug paraphernalia, and a firearm with
an obliterated serial number.

  Snipe was indicted for possession of a firearm with an
obliterated serial number in violation of 18 U.S.C. § 922(k)
and 18 U.S.C. § 924(a)(1)(B). Following his indictment,
Snipe and a co-defendant moved to suppress the illegal drugs
and the firearm on the ground that the evidence was the prod-
uct of an illegal entry. The district court denied that motion,
and Snipe subsequently pled guilty. At sentencing, Snipe
                        UNITED STATES v. SNIPE                       1315
objected to the finding of the Presentence Report (“PSR”) that
he was a prohibited person in possession of a firearm pursuant
to U.S. SENTENCING GUIDELINES MANUAL (“U.S.S.G.”)
§ 2K2.1(a)(6)(A). Snipe did not, however, object to the PSR’s
finding that he was a regular user of methamphetamine or his
own admission, contained in that report, that “he had probably
. . . used drugs a ‘couple of days’ ” before January 1, 2005.
Indeed, at sentencing, both Snipe and his counsel stated that
“around the time of the incident [he] had a meth problem.” On
that basis, the district court found, consistent with the PSR,
that Snipe was a prohibited person and sentenced him to 15
months imprisonment. Snipe now timely appeals.

                                    II

  Snipe challenges both his conviction and sentence. We
address each in turn.

A.    Snipe’s Conviction

   Snipe challenges his conviction on the ground that the dis-
trict court erroneously denied his suppression motion.3 “We
review de novo the denial of a motion to suppress, . . . while
the underlying factual findings are reviewed for clear error.”
United States v. Crawford, 

, 1053 (9th Cir.
2004) (en banc); accord United States v. Rowland, 

, 903 (9th Cir. 2006). Applying that standard, as set forth
below, we affirm Snipe’s conviction. The officers’ initial
entry was justified by exigent circumstances, and their subse-
quent observations of illegal drugs in plain view provided
probable cause for the search warrant that led to their finding
the firearm with an obliterated serial number.
  3
    The government conceded at Snipe’s plea colloquy that because there
was no formal plea agreement, Snipe retained the right to appeal the dis-
trict court’s suppression ruling. Thus, the government has waived any pro-
cedural bar to appealing pre-conviction motions that might be associated
with the entry of an unconditional guilty plea. See United States v. Jacobo
Castillo, 

, 954 (9th cir. 2007) (en banc).
1316                    UNITED STATES v. SNIPE
   “[W]arrants are generally required to search a person’s
home or his person unless ‘the exigencies of the situation’
make the needs of law enforcement so compelling that the
warrantless search is objectively reasonable under the Fourth
Amendment.” Mincey v. Arizona, 

, 393-94
(1978) (quoting McDonald v. United States, 

,
456 (1948)).4 “ ‘The need to protect or preserve life or avoid
serious injury is’ ” one such “ ‘justification for what would be
otherwise illegal absent an exigency or emergency.’ ” 

(quoting Wayne v. United States, 

, 212 (D.C.
Cir. 1963) (Burger, J.)). The district court relied on that doc-
trine in denying Snipe’s motion. In so doing, the district court
applied this court’s three-part test adopted in United States v.
Morales Cervantes, 

, 888 (9th Cir. 2000), which
required that:

      (1) The police must have reasonable grounds to
      believe that there is an emergency at hand and an
      immediate need for their assistance for the protection
      of life or property. (2) The search must not be pri-
      marily motivated by intent to arrest and seize evi-
      dence. (3) There must be some reasonable basis,
      approximating probable cause, to associate the emer-
      gency with the area or place to be searched.

(quoting People v. Mitchell, 

, 609 (N.Y.
1976)). The district court held the government met that test.

  [1] After the district court’s decision, the Supreme Court
decided Brigham City v. Stuart, 

(2006),
which was intended to resolve “differences among state courts
  4
    The Fourth Amendment provides that, “The right of the people to be
secure in their persons, houses, papers, and effects, against unreasonable
searches and seizures, shall not be violated, and no Warrants shall issue,
but upon probable cause, supported by Oath or affirmation, and particu-
larly describing the place to be searched, and the persons or things to be
seized.” U.S. CONST. amend. IV.
                       UNITED STATES v. SNIPE                     1317
and the Courts of Appeals concerning the appropriate Fourth
Amendment standard governing warrantless entry by law
enforcement in an emergency situation.” In Brigham City, the
Court began by reaffirming the principle that, “law enforce-
ment officers may enter a home without a warrant to render
emergency assistance to an injured occupant or to protect an
occupant from imminent injury.” 

to the stan-
dard governing such entries, the Court held that, as in other
Fourth Amendment contexts, “[t]he officer’s subjective moti-
vation is irrelevant” to determining whether such entries are
justified. Id.; see also Whren v. United States, 

,
813 (1996) (“[W]e have been unwilling to entertain Fourth
Amendment challenges based on the actual motivations of
individual officers.”). Instead, in determining whether such
entries are justified, Brigham City only asked—with reference
to the whole record—whether the circumstances, viewed
objectively, justify the 

, and whether
“the manner of the officers’ entry was also reasonable,” 

See also 

(holding the police met the first
test because “the officers had an objectively reasonable basis
for believing” a person inside the house was injured and the
violence was ongoing); 

(holding “[t]he manner
of the officers’ entry was also reasonable” because the police
repeatedly attempted to announce their presence).

   [2] Brigham City requires us to reconsider and revise Cer-
vantes in three critical respects.5 The first prong of Cervantes
survives Brigham City, and indeed remains the core of the
Fourth Amendment analysis of exigent circumstances. Con-
sidering the totality of the circumstances, law enforcement
must have an objectively reasonable basis for concluding that
there is an immediate need to protect others or themselves
  5
   Though we have noted Brigham City’s holding in the past, see, e.g.,
United States v. Black, 

, 1146 n.1 (9th Cir. 2006); United
States v. Martinez-Rodriguez, 

, 1096 (9th Cir. 2007), we
have not yet explicitly considered Brigham City’s effect on our decision
in Cervantes.
1318                   UNITED STATES v. SNIPE
from serious harm. Second, because Brigham City rejected
any subjective analysis, we reject Cervantes’ subjective sec-
ond prong and hold that law enforcement’s subjective motiva-
tions are irrelevant in determining whether the emergency
doctrine applies. Third, we also reject Cervantes’ third prong
—and Snipe’s attempt to engraft an expanded probable cause
inquiry onto that prong—as superfluous because Brigham
City failed to conduct any traditional probable cause inquiry.
Instead, the Court assumed that probable cause to associate
the emergency with the place to be searched exists whenever
law enforcement officers have an objectively reasonable basis
for concluding that an emergency is unfolding in that place.
Indeed, even before Brigham City, both the Second and Elev-
enth Circuits had held that, “in an emergency, the probable
cause element may be satisfied where officers reasonably
believe a person is in danger.” United States v. Holloway, 

, 1338 (11th Cir. 2002); accord Koch v. Brattle-
boro, 

, 169 (2d Cir. 2002). And finally, because
Brigham City explicitly considered the officers’ manner of
entry, we hold that any subsequent review of an entry pursu-
ant to the exigent circumstances doctrine must consider the
officers’ manner of entry.

   [3] Thus, in place of Cervantes, we now adopt a two-
pronged test that asks whether: (1) considering the totality of
the circumstances, law enforcement had an objectively rea-
sonable basis for concluding that there was an immediate
need to protect others or themselves from serious harm; and
(2) the search’s scope and manner were reasonable to meet
the need. Under that test, then, as previously under Cervantes,
if law enforcement, while “respond[ing] to an emergency, dis-
covers evidence of illegal activity, that evidence is admissible
even if there was not probable cause to believe that such evi-
dence would be 

.6
  6
   Snipe argues that any new test should include prongs considering “the
gravity of the underlying offense” and “the violent behavior the officers
                         UNITED STATES v. SNIPE                        1319
   Other circuits have reached similar conclusions. For
instance, the Sixth Circuit has held that in cases involving the
emergency doctrine, “[t]he government, in order to satisfy the
exigent-circumstances exception” must demonstrate that—
considering the totality of the circumstances—the search was
objectively reasonable because “there was a risk of serious
injury posed to the officers or others that required swift
action.” United States v. Huffman, 

, 783 (6th Cir.
2006). The Tenth Circuit—which before Brigham City
applied nearly the same three-part test as this circuit—has
held that Brigham City excised the second prong of the old
three part test and rejected any traditional probable cause
inquiry under the third prong. United States v. Najar, 451

witnessed outside of the home.” Neither argument has merit. The sugges-
tion that “the gravity of the underlying offense” should be part of Brigham
City’s test would be problematic because requiring officers to weigh the
severity of the ongoing emergency before responding “would dramatically
slow emergency response time, and would therefore be at odds with the
purpose of the emergency doctrine—allow[ing] police to respond to emer-
gency situations.” United States v. Russell, 

, 1092 (9th Cir.
2006) (internal quotation marks omitted).
   Snipe’s assertion that the police must witness ongoing violence before
responding to an emergency conflicts not only with the purposes underly-
ing the emergency doctrine but also with Brigham City’s express state-
ment that police officers do not have to wait for violence before 

(“The role of a peace officer includes preventing vio-
lence and restoring order, not simply rendering first aid to casualties.”);
see also United States v. Brown, 

, 1086 (7th Cir. 1995) (“We
do not think that the police must stand outside an apartment, despite legiti-
mate concerns about the welfare of the occupant, unless they can hear
screams. Doubtless outcries would justify entry, but they are not essen-
tial.” (internal citations omitted)); 3 WAYNE R. LAFAVE, SEARCH AND SEI-
ZURE: A TREATISE ON THE FOURTH AMENDMENT § 6.6 (4th ed. 2004) (“[B]y
design or default, the police are also expected to reduce the opportunities
for the commission of some crimes through preventative patrol and other
measures, aid individuals who are in danger of physical harm, assist those
who cannot care for themselves, resolve conflict, create and maintain a
feeling of security in the community, and provide other services on an
emergency basis.” (internal quotations omitted)).
1320                UNITED STATES v. SNIPE
F.3d 710, 715, 718 (10th Cir. 2006) (noting that Brigham City
did not “require probable cause in this type of exigent circum-
stance[ ]”). Consequently, the Tenth Circuit adopted a new
two-part test that asks, like the test we adopt here,“whether
(1) the officers have an objectively reasonable basis to believe
there is an immediate need to protect the lives or safety of
themselves or others, and (2) the manner and scope of the
search is reasonable.” 

   [4] In this case, the police meet both prongs of the test.
First, the officers had an objectively reasonable basis for
believing there was an immediate need to protect individuals
at the Snipe residence from serious harm. In determining
whether such an entry is objectively reasonable, the Supreme
Court has “consistently eschewed bright-line rules, instead
emphasizing the fact-specific nature of the reasonableness
inquiry,” and looked to the totality of the circumstances. Ohio
v. Robinette, 

, 39 (1996); accord United States v.
Banks, 

, 36 (2003) (“[W]e have treated reason-
ableness as a function of the facts of cases so various that no
template is likely to produce sounder results than examining
the totality of circumstances in a given case; it is too hard to
invent categories without giving short shrift to details that
turn out to be important in a given instance, and without
inflating marginal ones.”). As we consider the totality of the
circumstances here, we begin by observing that the officers
knew that they were responding to an emergency call by “a
hysterical male” who instructed the dispatcher to “[g]et the
police over here now” and that call alone largely justified
their response. Furthermore, it was objectively reasonable to
believe the caller had an emergency, even though that call did
not come in on the department’s 911 system, because, as the
police dispatcher testified, emergency calls routinely come in
on regular lines. That the call came in at 5 A.M. also contrib-
utes to the objective reasonableness of that perception.

  Snipe argues that the police should have done something to
verify the caller’s identity or the facts at Snipe’s home before
                     UNITED STATES v. SNIPE                 1321
entering the Snipe residence because of the possibility of
prank calls. We have previously rejected such a requirement
on the grounds that it “would dramatically slow emergency
response time, and would therefore be at odds with the pur-
pose of the emergency doctrine—allow[ing] police to respond
to emergency situations” in a timely manner. United States v.
Russell, 

, 1092 (9th Cir. 2006) (internal quota-
tion marks omitted). Indeed, in situations like the present,
where the dispatcher is prevented from verifying the caller’s
identity because the number that the caller called in on does
not populate, indicating either it was a blocked number or a
cell number, Snipe’s rule might prevent the police from
responding at all. We appreciate the risk of a “false positive”
emergency call and recognize that a show of police force in
response to a prank call is a substantial intrusion on the lives
of the prank’s victims. It is the nature of our own assessments
of what constitutes an emergency that the police will routinely
be summoned for matters that are not, in some objective
sense, real emergencies. We will not impose a duty of inquiry
on the police to separate a true cry for help from a less deserv-
ing call for attention because the delay may cost lives that
could have been saved by an immediate police response. The
possibility that immediate police action will prevent injury or
death outweighs the inconvenience we suffer when the police
interrupt our ordinary routines in response to what turns out
to be a non-emergency call.

   [5] The facts the officers confronted when they arrived at
the Snipe residence also underscore the entry’s objective rea-
sonableness. For example, when he arrived on the scene,
Rodriguez, who is Snipe’s neighbor, immediately noticed a
vehicle that he did not recognize. Rodriguez also saw an indi-
vidual he did not recognize running or walking into the resi-
dence. And, as Massey testified, the residence itself looked
suspicious because the front door was ajar and he could see
light coming from inside the house. Under these circum-
stances, the officers had an objectively reasonable basis to
1322                UNITED STATES v. SNIPE
believe there was an immediate need to protect others from
serious harm when they entered the Snipe residence.

   [6] The second prong of the exigent circumstances test con-
siders whether the manner and scope of the officers’ entry
was reasonable. We hold this entry was reasonable. Much like
the officers in Brigham City, Massey and Rodriguez knocked
and announced their presence before entering the residence.
When they saw an individual on a couch and others sitting at
a table, they again identified themselves and said they were
responding to an emergency call. In these circumstances, their
manner of entry was reasonable. The subsequent scope of
their search was also reasonable and confined to the areas of
the house likely to include individuals in harm’s way.

  [7] Accordingly, because we find that the district court did
not err in denying Snipe’s motion to suppress, we affirm
Snipe’s conviction.

B.     Sentencing Appeal

   Snipe appeals his sentence on the ground that the district
court erroneously sentenced him as a prohibited person pursu-
ant to U.S.S.G. § 2K2.1(a)(6)(A). We review the district
court’s interpretation of the Sentencing Guidelines de novo.
United States v. Cantrell, 

, 1279 (9th Cir.
2006). We review the district court’s application of the Sen-
tencing Guidelines to the facts of the case for abuse of discre-
tion, and our inquiry is limited to determining whether the
district court’s decision was “reasonable.” Gall v. United
States, 522 U.S. ___, No. 06-7949, slip op. at 7 (Dec. 10,
2007). We review the district court’s factual findings for clear
error. 

. Applying that standard, we
affirm Snipe’s sentence.

   [8] Snipe was sentenced consistent with U.S.S.G.
§ 2K2.1(a)(6)(A), which provides that “if the defendant . . .
was a prohibited person at the time the defendant committed
                    UNITED STATES v. SNIPE                 1323
the instant offense,” the defendant’s base offense level shall
be fourteen. A prohibited person is “any person defined in 18
U.S.C. § 922(g) or § 922(n),” U.S.S.G. § 2K2.1 cmt. n.3
(2004), which includes any person “who is an unlawful user
of or addicted to any controlled substances,” 18 U.S.C.
§ 922(g)(3). To successfully request an enhancement under
this provision, “the government must prove . . . that the defen-
dant took drugs with regularity, over an extended period of
time, and contemporaneously with his purchase or possession
of a firearm.” United States v. Prudy, 

, 813 (9th
Cir. 2001); see also United States v. Edmonds, 

,
953 (11th Cir. 2003) (“To support an offense enhancement
under § 2K2.1(a)(6), the government does not have to prove
the defendant was under the influence of a controlled sub-
stance at the time of his arrest. Instead, the government must
show the defendant was an ‘unlawful user’ of a controlled
substance during the same time period as the firearm posses-
sion.”). For U.S.S.G. § 2K2.1(a)(6)(A) to apply, the govern-
ment need only make that showing by a preponderance of the
evidence. See United States v. Charlesworth, 

,
1158 (9th Cir. 2000) (holding that the government bears the
burden of proving a defendant’s base level offense by a pre-
ponderance of the evidence); United States v. Howard, 

, 1090 (9th Cir. 1990) (holding that the government
should bear the burden of proof for any fact that the sentenc-
ing court would find necessary to determine the base offense
level by a preponderance of the evidence).

   [9] Furthermore, “the district court may rely on undisputed
statements in the PSR at sentencing” to find that the govern-
ment has met that standard, but “when a defendant raises
objections to the PSR, the district court is obliged to resolve
the factual dispute, see FED. R. CRIM. P. 32(i)(3)(B), and the
government bears the burden of proof to establish the factual
predicate for the court’s base offense level determination.”
United States v. Ameline, 

, 1085-86 (9th Cir.
2005) (en banc); see also United States v. Marin-Cuevas, 

, 895 (9th Cir. 1998) (“Because the only evidence
1324                   UNITED STATES v. SNIPE
before the sentencing court was the Presentence Report, the
preponderance of the evidence sustains the district court’s
finding.”). In other words, when a defendant objects to a
PSR’s factual findings, “[t]he court may not simply rely on
the factual statements in the PSR” to find that the government
has carried its burden. 

.

   [10] Relying on that language, Snipe asserts that the district
court erred when it grounded its finding that he was a prohib-
ited person entirely on the PSR’s conclusion that he was a
regular methamphetamine user since he maintained that he
was not a prohibited person. Snipe’s argument is without
merit because Ameline holds that a district court may not rely
exclusively on a PSR “[w]hen a defendant contests the factual
basis of a 

(emphasis added), and
Snipe made no objections to the factual findings in the PSR.7
See also United States v. Romero-Rendon, 

,
1163 (9th Cir. 2000) (holding a district court did not err in
grounding his sentencing findings entirely on the PSR
because the defendant “never questioned [its] factual accura-
cy”). Indeed, while arguing before the district court that
“there [was not] really any relation between the possession of
the .22 rifle and his drug use” because he did not use the gun
in connection with drug transactions (a point the attorney
acknowledged was irrelevant), Snipe’s attorney stated that he
used drugs during the relevant period. Far from contesting
Snipe’s drug use, his attorney conceded “that [Snipe] around
the time of the incident had a meth problem” and that it was
“undisputed he had drug issue and drug problems” during the
relevant period. Consequently, because Snipe conceded the
factual basis of the PSR, the district court did not err in basing
its conclusion that Snipe was a prohibited person on the PSR.
  7
   The PSR grounded its conclusion that Snipe was a regular user of
methamphetamine on Snipe’s own statements to police that he was a user
of controlled substances, “he had probably used drugs a ‘couple of days
before’ [January 1, 2005],” he began regular usage at 18 or 19, he was a
heavy user of methamphetamine in 2004, he used about three times per
week throughout 2004, and he had spent $10,000 on methamphetamine.
                    UNITED STATES v. SNIPE                1325
   Snipe’s other argument that his sentence should be
overturned—that “the disputed facts proving he is an ‘unlaw-
ful user’ should [have] go[ne] to a jury to decide under the
recent decision in United States v. Booker,”—also lacks merit
for essentially the same reason. Snipe never disputed the facts
underlying his sentence; he conceded them. Consequently, we
reject Snipe’s second argument and affirm his sentence.

                              III

   For the forgoing reasons, Snipe’s conviction and sentence
are AFFIRMED.