This case requires us to consider whether the emergency doctrine or implied consent can support a warrantless search of a home on suspicion that a 9-1-1 caller or lurking predator was inside.

I

On Saturday, December 23, 2003, Willie Russell, Jr., placed two calls to the Sacramento Sheriffs Office (SSO) 9-1-1 dispatcher. In the first emergency call, Russell identified himself as “Gregory Hines,” and explained to the operator that a gun went off and hit him in the foot, that he was wounded and in pain, and that he wanted the dispatcher to call an ambulance. The transcript of the first call shows that the Fire Dispatcher and the SSO Dispatcher were confused as to whether the caller had been shot, or had shot himself. After Russell’s call was disconnected, the SSO Dispatcher said to the Fire Dispatcher “[the caller] didn’t really confirm that he shot himself. He just said a ‘gun went off.’ ” Each patrol car contained a mounted computer system and monitor, known as a “Mobile Data Terminal,” which allows field officers to receive *1088 information pertinent to their calls through a “Computer Aided Dispatch,” or CAD, which updates text provided by 9-1-1 dispatchers on screens in the police officers’ cars. In this case, the CAD Event Report displayed to responding officers: “male stated gun went off and he shot [sic] in foot.”

Russell called back and spoke to a second emergency dispatcher, giving his real name and address and stating, “I shot myself in the foot.” Over the course of the phone call, Russell explained that he was “moving” the gun out of his bedroom closet when it went off. When asked whether he knew where the gun was currently, Russell first stated, “I don’t know,” then stated that he “left [the gun] upstairs somewhere. I dropped it on top of stuff on the floor.” Russell also stated that “my girlfriend is going to kill me.” Police were aware of Russell’s comments; the CAD Event Report displayed: “[Willie is] sayin that his gf [girlfriend] is goin to kill him when she finds out what he did ... gf not @ resd rite now[sic].”

The dispatchers asked whether Russell was alone, and he twice responded that nobody else was present. Again, the CAD Event Report reported to the responding officers that “Willie Russell ... sed [sic] he is home alone.” Later in the phone call, the dispatcher apparently overheard two unidentified female voices and asked whether there were other people there at that point, but Russell did not respond. The transcript of the phone call shows that female voices could be heard asking about the gun and whether Russell planned to give it to the police. An unidentified female voice asked: “Where’s the gun at? Are you going to give ‘em the gun?’ ” The CAD Event Report informed the officers that the dispatcher “heard male & fem voice in bkgrnd askn what was goin on[sic].”

Russell told the dispatchers that he had opened the front door for the police:

After his first call, the emergency dispatchers alerted police, who initially anticipated finding an injured man named “Gregory Hines,” the pseudonym Russell supplied to the first emergency dispatcher. While en route the officers received updated information that a second man, “Willie Russell,” was injured. As the officers neared Russell’s house, the dispatcher informed them that the injured man did not know where the gun could be located, and that the injured man had opened the door for the police. Neither the police nor the emergency dispatchers were aware that Willie Russell and Gregory Hines were one and the same. 1

Deputy Summer Elliott arrived near the scene first but waited outside the cul-de-sac entrance to the street until other units arrived. When asked why she did not enter the neighborhood herself, Deputy Elliott responded that “it is not safe to do so by myself with the unknown circumstances that was [sic] going on at the house.... A gun was discharged, and we don’t really know what’s going on inside.” *1089 Similarly, Sergeant Roger Dillon explained that “Deputy Elliott staged around the corner. It’s a safety issue. We don’t go to those kind of calls by ourselves because of — they’re not stable and the potential of getting hurt. So she staged around the corner.” When other units arrived, Deputy Elliott, along with Sergeant Roger Dillon and Deputy Brian Templeton, entered the neighborhood.

Deputy Elliott testified that she saw a man — Russell, though Deputy Elliott did not know this yet — “hopping out to the car with two other females coming out of the garage door.” Sergeant Dillon noted that there were two women with the injured man, though he had expected him to be alone. He testified that:

The other officers were not asked whether they expected Russell to be alone.

Deputy Elliott ordered Russell out of the car and began questioning him, but kept her weapon holstered. When Deputy Elliott asked Russell to identify himself, he refused. Deputy Elliott was similarly rebuffed when she asked Russell “what happened there.” Russell did not express to Deputy Elliott any objection to the entry of the other officers into the residence.

While Deputy Elliott was questioning Russell outside the house, Sergeant Dillon and Deputy Templeton immediately entered the house with their guns drawn. Sergeant Dillon testified that “for my safety, I drew my gun and kept it in a ready position where I could engage anyone who might pop up out of a closet, out of a doorway, out of anywhere.” Sergeant Dillon explained that his “intent was to go through the house to look to see if there were any other victims inside the residence, anyone that was injured and needed medical attention, or if there was a suspect that may have injured the subject who in the event claimed to have been shot in the foot.” He testified that “I was looking for another victim. And I was looking for possibly an armed subject inside the house.” Sergeant Dillon then found the weapon in plain view in Russell’s bedroom, but found no other person — injured or otherwise.

Russell was charged with a violation of 18 U.S.C. § 922 (g)(1), which makes unlawful the possession of a firearm by a convicted felon. Russell moved to suppress the gun evidence. The district court denied the motion after an evidentiary hearing, holding that the exigent circumstances exception supported the search, and in the alternative, that Russell had consented to the search of his residence:

Russell subsequently entered a guilty plea pursuant to an agreement that reserved his right to appeal the denial of his motion to suppress. 2

*1090 II

Russell contends that the warrant-less search cannot be sustained under the emergency doctrine. Our case law recognizes that the emergency doctrine, an exception to the warrant requirement, may support a warrantless search “if a police officer, while investigating within the scope necessary to respond to an emergency, discovers evidence of illegal activity, that evidence is admissible even if there was not probable cause to believe that such evidence would be found.” United States v. Cervantes, 219 F.3d 882, 888 (9th Cir.2000). See also United States v. Stafford, 416 F.3d 1068, 1073 (9th Cir.2005).

The emergency doctrine derives from Mincey v. Arizona, 437 U.S. 385 , 98 S.Ct. 2408 , 57 L.Ed.2d 290 (1978), which recognized police officers’ community care-taking function. See id. at 392 , 98 S.Ct. 2408 (noting that the Court did “not question the right of the police to respond to emergency situations” without a warrant). United States v. Cervantes — building on Mincey — adopted three requirements for the emergency doctrine:

219 F.3d at 888 (quoting People v. Mitchell, 39 N.Y.2d 173 , 347 N.E.2d 607, 609 , 383 N.Y.S.2d 246 (N.Y.1976)). See also United States v. Martinez, 406 F.3d 1160, 1164 (9th Cir.2005); Martin v. City of Oceanside, 360 F.3d 1078, 1082 (9th Cir.2004); United States v. Bradley, 321 F.3d 1212, 1214 (9th Cir.2003).

A

Russell first argues that the police did not have “reasonable grounds to believe that there [was] an emergency at hand and an immediate need for their assistance for the protection of life.” Cervantes, 219 F.3d at 888 .

1

Our analysis of the record indicates that even though the police observed that one man had exited the residence before they arrived, there was confusion as to whether this was the only injured person. The police had reason to believe that there were two injured men at Russell’s residence — one named Gregory Hines and the other named Willie Russell. Indeed, the police received a variety of conflicting data. They were told first, that one person had been shot in the foot; then another shot himself in the foot; then the police were told the caller was alone; then that his girlfriend was going to kill him; and then that Russell might not be alone. When the police finally arrived at Russell’s home, they found one injured person (rather than two) in the driveway (rather than in the house) accompanied by two women (rather than alone). Given the substantial confusion and conflicting information, the police were justified in searching the house in order to determine whether there were other injured persons, as their information indicated was the case.

2

Russell next argues that it was “manifest” that only one person had placed two phone calls. We disagree. Even in retrospect, the officers’ confusion is understandable. In Russell’s first call, the emergency dispatch operator noted that *1091 the victim stated that he had been shot, not that he had shot himself. When Russell placed a second call and spoke with a different emergency operator and stated that he had shot himself, the circumstances he described were different. Even with perfect information and sufficient time to digest and analyze it, the police would still have been justified in entering the house. 3 Thus, given the circumstances, it cannot be said that the situation was clear, or that the fact of a sole injured person was evident, or even that the shooting had been accidental.

Even if the situation were clear in hindsight, however, the police had only a few minutes in which to determine whether a lurking predator or injured person in need of assistance might be inside the house. It is unreasonable to expect the police to piece together a perfectly coherent picture in the scant minutes they had to digest the constantly-updated and conflicting information. See Graham v. Connor, 490 U.S. 386, 397 , 109 S.Ct. 1865 , 104 L.Ed.2d 443 (1989) (cautioning against second-guessing police officers, who “are often forced to make split-second judgments — in circumstances that are tense, uncertain, and rapidly evolving”).

3

Russell also argues that our prior cases emphasize that the officers must first determine that there was an emergency before entering the house. In United States v. Bradley, for example, the court noted that “before the officers entered the house, they took several other steps,” including knocking on the front door and speaking with neighbors before entering the house. 321 F.3d at 1215 . In United States v. Deemer, the officers, responding to an emergency call from an intoxicated caller, only made an emergency entry after the woman who answered the door stated that she was alone, but police heard movement behind the door. 354 F.3d 1130, 1132 (9th Cir.2003). Russell also points to Martin v. City of Oceanside, where the police, responding to a concerned father’s call about his daughter, spoke to neighbors before entering the house. 360 F.3d at 1082 . Finally, in United States v. Martinez, we affirmed the district court’s denial of a motion to suppress based on the emergency doctrine where the police responded to a domestic violence call and entered the house only after hearing screaming coming from inside. 406 F.3d 1160 . Based on this case law, Russell argues that the police should have stopped to speak with him, or his mother or girlfriend who were helping him into the car, to determine whether there were additional injured persons in the house.

Russell’s argument is unconvincing for several reasons. Most obviously, our case law clearly requires that the police must only have “reasonable grounds to believe that there is an emergency at hand and an immediate need for their assistance for the protection of life.” Cervantes, 219 F.3d at 888 . Russell’s analysis, however, would incorporate a fourth requirement into the emergency doctrine: that the police obtain independent verification or other information relating to the emergency before entering the house. 4 We decline to read an *1092 additional limitation into the emergency-exception’s settled case law. Further, such a requirement would dramatically slow emergency response time, and would therefore be at odds with the purpose of the emergency doctrine — “allowpng] police to respond” to emergency situations. 5 Mincey, 437 U.S. at 392 , 98 S.Ct. 2408 . The only requirement — which the police easily met — is that they have “reasonable grounds to believe that there is an emergency at hand.” Given the circumstances, the officers and dispatchers clearly believed there was an ongoing emergency. 6

Further, Bradley, Martinez, and Deem-er do not stand for the proposition for which Russell cites them. In each of these cases, the police had to take additional steps to determine whether there was an emergency that justified entry in the first place. In Bradley , the police “could not locate [the missing child] in the places [his mother] said he was.” 321 F.3d at 1215 . In order to determine whether there was actually an emergency that justified entry, the police took steps to determine if the child was with neighbors before entering Russell’s house. Similarly, in Martin , the police were responding to a father concerned about his daughter — -who had not answered her phone — and were therefore uncertain whether there was an actual emergency. In Deemer, again, the police were uncertain whether there was any emergency basis for entering the motel room, so they spoke to the woman who answered the door. In Martinez , in contrast, the police entered the house because the circumstances — a bruised female outside and screaming coming from the inside — indicated that there was an emergency. These cases indicate that the police only must take additional steps if they otherwise lack reasonable grounds to believe there is an emergency. Cervantes requires no more, and our ease law imposes no additional restriction beyond the reasonable grounds requirement.

Applying these cases to the present facts, the police had good reason to believe that there was an emergency and did not need independent confirmation: they had already received two emergency phone calls, saw only one severely injured person when they arrived at the scene, and therefore had reasonable grounds to believe another might be inside the house. 7 Therefore, the district court did not clearly err in concluding that the officers had reasonable grounds to believe that there *1093 was an emergency requiring their immediate intervention.

B

Next, Russell suggests improper motive. We are satisfied that the district court did not clearly err in determining that the police entered Russell’s house motivated by an intent to determine if there were any remaining victims or lurking predators who might harm or harass emergency personnel. The police entered the house with their guns drawn and swept through the house in less than two minutes, a style of search clearly inconsistent with an intent to discover and seize evidence. 8 In any event, the district court made a factual decision to credit the officers’ testimony regarding their motive, concluding that it was benign. Even if the facts support other conclusions, they do not compel one in particular. The district court’s conclusion—that the discovery of the evidence was only ancillary to the officers’ main goal—was not clearly erroneous.

C

Finally, Russell suggests that the search was excessive. Our review indicates that the district court did not clearly err in determining that the police had a reasonable basis to associate the places searched with the emergency in question. The police searched only areas in which a potential criminal could have been hiding in wait and areas in which an additional victim would have been waiting for assistance. The police searched no drawers or other areas where an armed or injured person could not conceivably have been hidden.

III

Russell also challenges the district court’s alternative holding that consent to the search was implied. In light of our conclusion that the search was supported by the emergency doctrine, we need not address the implied consent issue.

IV

Russell urges that a limited Ame-line remand should be available because he has an “unpreserved Booker error that may have affected [his] substantial rights, and the record is insufficiently clear to conduct a complete plain error analysis.” United States v. Ameline, 409 F.3d 1073, 1074 (9th Cir.2005) (en banc). Russell was indeed sentenced under the Sentencing Guidelines pursuant to a statute without a mandatory minimum and did not present a Sixth Amendment challenge. Therefore, “a limited remand to the district court is appropriate for the purpose of ascertaining whether the sentence imposed would have been materially different had the district court known that the sentencing guidelines were advisory.” Id. See also United States v. Moreno-Hernandez, 419 F.3d 906, 916 (9th Cir.2005).

AFFIRMED IN PART; REMANDED IN PART.

. The parties did not supply a record of any radio transmissions between dispatchers and the responding officers, so our analysis follows the facts presented in the exhibits and testimony from the pretrial suppression hearing.

. Whether exigent circumstances support a warrantless search is a mixed question of law and fact which we review de novo. United States v. Bynum, 362 F.3d 574, 578-79 (9th Cir.2004); United States v. Zermeno, 66 F.3d 1058, 1063, n. 2 (9th Cir.1995). We review findings of fact underlying the district court's *1090 determination for clear error. Bynum, 362 F.3d at 578-79 .

. Russell attempts to rely on the collective knowledge doctrine, which extends to the knowledge of the police dispatchers. See United States v. Fernandez-Castillo, 324 F.3d 1114, 1118 (9th Cir.2003). However, because Russell spoke to two different emergency operators, no single operator was aware that the same injured person had placed both calls.

. We agree with the dissent's characterization of the emergency exception as "well-delineated.'' Dissent at 1094 (quoting Martinez, 406 F.3d at 1164 ). This is precisely why we decline to read a further requirement into the exception.

. Indeed, the facts of this case illustrate why such a requirement would be dangerous: had the police been forced to stop and speak with Russell, who steadfastly refused to divulge any information to officers on the scene, their capability to rescue a potentially injured person inside would have been dramatically handicapped.

. What's more, the district court concluded that the police believed there was an emergency. While the dissent reaches a different conclusion, Dissent at 1095-96, we may not disturb the district court's factual conclusion unless clearly erroneous, which it is not. Bynum, 362 F.3d at 578-79 .

. The dissent argues that in Russell's second call he cleared up the confusion he created by "describing] what had happened in detail" and "verifying] that he was alone in the house.” Dissent at 1095. However, Russell never explained to the emergency dispatcher that he had previously reported a similar— though not identical — shooting under a different name. Similarly, shortly after Russell "verified that he was alone," dispatchers overheard voices in the background. Dissent at 1095. Even if an omnipotent dispatcher had concluded that one of the voice's was that of Russell's girlfriend, this could hardly assuage the officers' concern — after all, Russell had just stated that his girlfriend was going to kill him. See supra at 1088. Russell may have intended to explain and defuse the situation, but we conclude, like the district court, that he failed miserably.

. Following the discovery of the gun, and after radioing to fire and medical assistance teams that the scene was clear, the police engaged in a general search of the residence. As noted by the district court, however, the police initiated this search after discovering the gun. It is not, therefore, relevant to the question whether the initial emergency search, which was extremely brief, was proper.