                    FOR PUBLICATION
  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT

UNITED STATES OF AMERICA,                       No. 03-30456
                Plaintiff-Appellee,                D.C. No.
               v.
                                              CR-02-00108-1-JKS
ROBERT F. COMBS,                                 ORDER AND
             Defendant-Appellant.                 AMENDED
                                                  OPINION

         Appeal from the United States District Court
                  for the District of Alaska
         James K. Singleton, Chief Judge, Presiding

                     Submitted July 8, 2004*
                       Anchorage, Alaska

                     Filed January 11, 2005
                     Amended June 16, 2005

  Before: Cynthia Holcomb Hall, Andrew J. Kleinfeld, and
           Kim McLane Wardlaw, Circuit Judges.

                   Opinion by Judge Wardlaw




  *This panel unanimously finds this case suitable for decision without
oral argument. See Fed. R. App. P. 34(a)(2).

                                7177
7180               UNITED STATES v. COMBS


                         COUNSEL

Lance C. Wells, Anchorage, Alaska, for the appellant.

Jo Ann Farrington, Assistant United States Attorney, Anchor-
age, Alaska, for the appellee.


                          ORDER

  The opinion filed January 11, 2005 is amended as follows:

1) Page 406: Delete the sentence beginning, “Because there
was no . . .” and replace with “Because there was no Fourth
Amendment violation, we affirm Combs’ conviction, but we
issue a limited remand as to Combs’ claim of Sixth Amend-
ment sentencing error. See United States v. Ameline, No. 02-
30326, slip op. at 6368-71 (9th Cir. June 1, 2005) (en banc).”

2) Delete the current Section III and add a new Section III as
follows:

                             III.

  Our original opinion did not address Combs’ assertion of
Sixth Amendment error. Because Combs did not challenge his
                    UNITED STATES v. COMBS                 7181
sentence on Sixth Amendment grounds in the district court,
we grant a “limited remand” pursuant to United States v.
Ameline, No. 02-30326, slip op. at 6368-71 (9th Cir. June 1,
2005) (en banc).

  AFFIRMED AND REMANDED.

 With these amendments, Combs’ petition for rehearing is
DENIED as moot.


                          OPINION

WARDLAW, Circuit Judge:

   Robert Combs appeals his conviction, following a bench
trial, for maintaining a place for the manufacture of controlled
substances, attempting to manufacture methamphetamine,
being a felon in possession of a firearm, and criminal forfei-
ture. Combs asserts the district court erred in denying his
motion to suppress evidence resulting from a search of his
residence because the police did not physically knock on his
door and therefore failed to adequately “knock and announce”
before executing the search warrant. Whether the Fourth
Amendment requires an actual “knock” on the door of a sus-
pect’s home before a search can be conducted is an issue of
first impression in our circuit. We hold that under the totality
of the circumstances presented in this case, the police acted
reasonably in executing the warrant without first physically
“knocking” on the front door of Combs’s residence. Because
there was no Fourth Amendment violation, we affirm Combs’
conviction, but we issue a limited remand as to Combs’ claim
of Sixth Amendment sentencing error. See United States v.
Ameline, No. 02-30326, slip op. at 6368-71 (9th Cir. June 1,
2005) (en banc).
7182                UNITED STATES v. COMBS
                               I.

                         Background

   After receiving an anonymous tip, Anchorage Police began
investigating possible methamphetamine production and drug
trafficking at the home of Robert Combs. A search warrant
issued, based upon information obtained from the investiga-
tion, to search Combs’s home at any time of the day or night
for evidence of misconduct involving controlled substances.

   On the morning of September 12, 2002, the search warrant
was executed with the assistance of a Crisis Intervention
Response Team (“CIRT”), a tactical police unit trained and
equipped to handle high risk raids on suspected methamphet-
amine labs, which may involve exposure to various flamma-
ble, explosive, and toxic chemicals. The CIRT officers wore
protective gear consisting of flash fire resistant Nomex bala-
clavas, gas masks, one-piece Nomex flight suits and Kevlar
vests with police insignia.

   Anchorage Police Lieutenant Steven Smith was in com-
mand. He had spent nearly seventeen years with the Anchor-
age Police Department, ten of which were with the CIRT.
During those ten years, Lieutenant Smith participated in
somewhere between thirty to forty warrant services. In addi-
tion to Lieutenant Smith, approximately ten to twelve CIRT
officers were involved in the entry of Combs’s house. Six
officers were to make the actual entry at the door at the back
of the house, while four to six additional officers were to pro-
vide cover.

  When Lieutenant Smith arrived at the scene, he noticed
smoke coming from the chimney and an acrid smell in the air.
He also noticed what appeared to be an open flame at a win-
dow in the northeast corner of the house. Because the smoke
and flame indicated that the occupants might be involved in
the dangerous process of cooking methamphetamine, he
                   UNITED STATES v. COMBS                 7183
became concerned for the CIRT unit’s safety. There were
flood lights and two surveillance cameras attached to the
house and the windows to the garage were papered over. The
officers knew the house was occupied because a woman was
seen entering the house just before the warrant was executed.

   Service of the warrant commenced when Lieutenant Smith
parked his marked police car, with the overhead lights flash-
ing, in front of the house and began making announcements
regarding the warrant service over the public address system
in the front grill of the vehicle. Lieutenant Smith repeatedly
publicly announced, for a period of thirty seconds to a minute,
“Anchorage Police with a warrant for 1502 West 32nd Ave-
nue.”

   Although Lieutenant Smith could not see the approach of
the CIRT from the south of the building, he heard the entry
team officers around the location announcing, “Anchorage
Police with a warrant.” Sergeant Soto, a member of the CIRT,
was part of the group approaching the back door to make
entry. Soto’s role during the search was to be the “breacher.”
He carried a metal battering ram and halogen tools for this
purpose. When the team members finished assembling at the
door, they waited while Lieutenant Smith continued to
announce the police presence with a search warrant. At some
point, Soto’s team leader told him to breach. Soto hit the door
on the doorknob side with the battering ram four or five times
without success. His team leader instructed him to hit the
hinged side of the door. After two hits, the door broke open
and the officers entered the house. Soto estimated that he
spent a total of ten to twelve seconds pounding on the door
with the battering ram.

   The subsequent search of the house resulted in the seizure
of, among other things, evidence of an active methamphet-
amine lab, firearms, and currency from drug trafficking. Offi-
cers also obtained a statement from Combs after he was
placed under arrest and advised of his rights. Combs moved
7184                    UNITED STATES v. COMBS
for suppression of all of this evidence, arguing in part that the
manner of execution of the search warrant was unreasonable
because the police failed to properly “knock and announce”
before breaching the door.1

                                     II.

                               Discussion

   [1] The common-law principle that law enforcement offi-
cers should “knock and announce” their presence and author-
ity before entering a dwelling is part of the reasonableness
inquiry under the United States Constitution’s Fourth Amend-
ment guarantee against unreasonable searches and seizures.
Wilson v. Arkansas, 514 U.S. 927, 934 (1995).2 However,
“[t]he Fourth Amendment’s flexible requirement of reason-
ableness should not be read to mandate a rigid rule of
announcement that ignores countervailing law enforcement
interests. . . . [T]he common-law principle of announcement
  1
     Combs mistakenly frames the issue as whether the state police com-
plied with 18 U.S.C. § 3109 in the course of serving the search warrant on
his house. However, 18 U.S.C. § 3109 governs the conduct of federal offi-
cers, not state officers such as those involved here. United States v. Valen-
zuela, 596 F.2d 824, 829-30 (9th Cir. 1979). Accordingly, Combs should
have framed the issue as whether the state police acted reasonably under
the Fourth Amendment. Nevertheless, because 18 U.S.C. § 3109 is the
federal codification of the common-law knock and announce principle, it
is relevant to our analysis.
   2
     Two types of factual patterns emerge in knock and announce cases:
cases where there is no knock or announcement prior to entry, a so called
“no-knock” entry, see, e.g., Wilson v. Arkansas, 514 U.S. 927, 937 (1995)
(police did not knock or announce prior to entering house), and cases
where the court is analyzing the reasonableness of the announcement
given by the police, see, e.g., U.S. v. Banks, 540 U.S. 31 (2003) (discuss-
ing whether the length of time after police announcement was sufficient
and finding announcement to be reasonable). The Supreme Court has
noted that the same criteria bear upon the reasonableness inquiry in both
types of cases; therefore we apply the same analysis to both types of cases.
See id. at 35.
                       UNITED STATES v. COMBS                      7185
was never stated as an inflexible rule requiring announcement
under all circumstances.” Wilson v. Arkansas, 514 U.S. 927,
934 (1995).3 A physical knock is only one factor to be consid-
ered in the reasonableness inquiry and is not determinative.
See U.S. v. Chavez-Miranda, 306 F.3d 973, 980 (9th Cir.
2002) (considering many factors in determining whether
police entry was reasonable). Thus we must examine the total-
ity of circumstances to determine whether a given search was
reasonably executed.

A.    The “Knock and Announce” Rule

   That the government must announce its presence before
entering a private home is a longstanding principle. In Wilson,
the Supreme Court traced its origins to English common law.
514 U.S. at 931-33 (surveying cases applying the knock and
announce rule from the 17th and 18th Centuries and citing
Blackstone, Sir Matthew Hale, and William Hawkins). The
Court noted that the “common-law knock and announce prin-
ciple was woven quickly into the fabric of early American
law.” Id. at 933. It held that “the method of an officer’s entry
into a dwelling [is] among the factors to be considered in
assessing the reasonableness of a search or seizure.” Id. at
934. The Wilson Court left to the circuit courts the develop-
ment of circumstances under which an entry is deemed rea-
sonable under the Fourth Amendment. Id. at 936.

   While the definition of “reasonableness” was left for
another day, the Wilson opinion does provide guidance in
determining what is reasonable. The Court set forth a non-
exhaustive list of occasions when “the presumption in favor
of announcement necessarily . . . give[s] way to contrary con-
siderations.” Id. at 935. It identified circumstances when the
rule need not be strictly followed, such as when there is a
  3
    We have jurisdiction pursuant to 28 U.S.C. § 1291. We review the dis-
trict court’s conclusions of law de novo and factual findings for clear
error. United States v. Hammett, 236 F.3d 1054, 1057 (9th Cir. 2001).
7186                 UNITED STATES v. COMBS
threat of physical violence against law enforcement, when
chasing a fleeing felon, or where evidence “would likely be
destroyed if advance notice were given.” Id. at 936. The Court
was careful to note that the examples it gave were not a “com-
prehensive catalog of the relevant . . . factors,” but rather
illustrations of circumstances that may carry weight in a rea-
sonableness determination. Id.

   Since Wilson, the Court has reiterated that the knock and
announce principle is a part of the reasonableness inquiry
rather than a prerequisite for constitutional entry. See U.S. v.
Banks, 540 U.S. 31, 35-36 (2003) (noting that the Court has
“fleshed out” the notion of reasonable execution on a “case by
case” basis “largely avoiding categories and protocols for
searches”). Instead of setting bright-line, rigid rules, the Court
has “treated reasonableness 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”
because “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.” Id at 36. See
also Richards v. Wisconsin, 520 U.S. 385 (1997) (rejecting
categorical exception to the knock and announce requirement
for felony drug cases; favoring instead a case-by-case analy-
sis).

B.     The “Knock”

   With this guidance from the Supreme Court, we cannot
accept Combs’s assertion that without a literal knock, the
entry into his home was per se unreasonable under the Fourth
Amendment. Nor can we accept the government’s position
that a knock is never necessary under the Fourth Amendment.
Neither of these strict categorical approaches is consistent
with the reasonableness inquiry laid out by the Supreme
Court. See Banks, 540 U.S. at 41 (rejecting both the argument
that damage to property should not be part of the reasonable-
ness analysis and the argument that damage to property is a
                     UNITED STATES v. COMBS                   7187
heightened factor). Rather, “[t]he focus of the ‘knock and
announce’ rule is properly not on what ‘magic words’ are spo-
ken by the police, or whether the police rang the doorbell, but
rather on how these words and other actions of the police will
be perceived by the occupant.” U.S. v. Spikes, 158 F.3d 913,
925 (6th Cir. 1998) (quotation omitted).

   [2] The general practice of physically knocking on the
door, announcing law enforcement’s presence and purpose,
and receiving an actual refusal or waiting a sufficient amount
of time to infer refusal is the preferred method of entry. See
Banks, 540 U.S. at 43. This method is preferable because it
provides a clear rule that law enforcement can follow. It also
promotes the goals of the knock and announce principle: pro-
tecting the sanctity of the home, preventing the unnecessary
destruction of private property through forced entry, and
avoiding violent confrontations that may occur if occupants of
the home mistake law enforcement for intruders. See Wilson,
514 U.S. at 935-36; Spikes, 158 F.3d at 925.

   [3] Although “knock and announce” is the preferred
method of entry, given the totality of the circumstances in a
particular case, it is not invariably required by the Fourth
Amendment. In some circumstances, it may be necessary to
dispense with the knock and announcement entirely. See, e.g.,
U.S. v. Peterson, 353 F.3d 1045, 1049 (9th Cir. 2003) (finding
no-knock entry permissible because knock would have been
futile, there was potential destruction of evidence, and danger
to police officers). Other circumstances may warrant a knock
and announcement, but only a relatively short delay before a
forced entry. See, e.g., Banks, 540 U.S. at 39 (finding 15-20
second wait before entry reasonable given time of day and
destructibility of the evidence). Under other circumstances,
the police may not be justified in breaking down a door until
they have waited a more extended period of time to infer a
refusal of entry. See, e.g., id. at 41 (noting that “[p]olice seek-
ing a stolen piano may be able to spend more time to make
7188                UNITED STATES v. COMBS
sure they really need the battering ram” since that evidence is
not easily destroyed).

   [4] To determine whether an entry is reasonable, we must
consider all the circumstances surrounding the entry, includ-
ing, but not limited to, officer safety, Wilson, 514 U.S. at 936,
time of day, Banks, 540 U.S. at 40, destructibility of evidence,
id., the size of the residence, the nature of the offense, and any
other observations by law enforcement that would support a
forced entry. See Bynum, 362 F.3d at 581; Chavez-Miranda,
306 F.3d at 980. We also must examine what, if any, notice
the police gave before entry and the likelihood that the notice
alerted those inside the home to the officer’s presence and
purpose. See Spikes, 158 F.3d at 927 (considering the police’s
bullhorn announcement an important factor in favor of rea-
sonableness of entry). A physical knock, or any other one fac-
tor, is not dispositive.

   In U.S. v. Spikes, the Sixth Circuit adopted this view in a
case involving the “knock” component of knock and
announce. In Spikes, the police announced their presence
while running up the stairs to the front porch. Spikes, 158 F.3d
at 919. Upon reaching the front door, they knocked on the
door for about four seconds. Id. The defendant argued that in
evaluating whether the police waited a reasonable amount of
time before knocking down the door, the court should mea-
sure from the time of the knock, four seconds, and ignore the
15-30 seconds of announcement prior to the knock while the
police ran up the stairs. Id. at 924. The Spikes court rejected
this argument and instead analyzed the reasonableness of law
enforcement’s entry given the totality of the circumstances—
taking into account the announcement prior to the knock, as
well as the knock itself. Id. at 925.

C.     Application of the Reasonableness Test

  [5] We conclude that the entry was reasonable in this case,
even though a literal knock was not made. First, there was
                        UNITED STATES v. COMBS                         7189
reason for the officers to be concerned for their safety. The
house was equipped with security cameras and flood lights.
Windows were papered over, suggesting that the occupants of
the home were concerned with protecting their illegal
methamphetamine laboratory. See U.S. v. Cline, 349 F.3d
1276, 1289-90 (10th Cir. 2003) (finding the presence of sur-
veillance cameras a factor in favor of the reasonableness of
law enforcement’s method of entry). In addition, after arriving
at the scene, Lieutenant Smith noticed smoke coming from
the chimney and what he thought to be an open flame at a
window, indicating that the occupants may have been cooking
methamphetamine—a dangerous process of mixing several
highly explosive chemicals over an open flame.4 Given these
circumstances, it was reasonable for Lieutenant Smith to limit
the amount of time his officers spent outside but within arm’s
reach of the house.5

   [6] Second, the officers announced their presence to the
extent possible given their legitimate safety concerns. They
parked in front of the house in a marked police car with the
overhead lights flashing. Lieutenant Smith repeatedly
announced over a loudspeaker, “Anchorage Police with a
warrant for 1502 West 32nd Avenue.” Given the small size of
the house, the time of day, the officer’s knowledge that there
was at least one occupant awake in the house, and that offi-
cers on the other side of the house heard the announcement,
the district court’s finding that “the residents of Combs’ small
home heard the police announce their presence and demand
  4
    See Methamphetamine Laboratory Identification and Hazards, United
States Department of Justice, National Drug Intelligence Center, available
at http://www.usdoj.gov/ndic/pubs7/7341/#hazards (brochure describing
hazards involved in producing methamphetamine).
  5
    We take care to note that “[t]he officers’ concerns were not based on
generalizations or stereotypes of drug dealers or narcotics investigations,
but rather on particularized, articulable, and reliable information.” U.S. v.
Bynum, 362 F.3d 574 (9th Cir. 2004). Thus, our analysis is in line with the
Supreme Court’s rejection of categorical exceptions for drug cases. Rich-
ards v. Wisconsin, 520 U.S. 385 (1997).
7190                UNITED STATES v. COMBS
entry and disregarded that request” was not clearly erroneous.
Moreover the occupants of the home could have had no doubt
that the police had arrived to search their residence as the
announcements repeatedly gave the street address of their
home.

   Given these circumstances, we find that law enforcement’s
actions were reasonable and the warrant’s execution complied
with the requirements of the Fourth Amendment. We do not
suggest that the absence of any of these factors would compel
a contrary conclusion. The factors we have listed are simply
part of our “case by case” examination. Just as it is not per-
missible to “turn[ ] the notion of a reasonable time under all
the circumstances into a set of sub-rules,” likewise it is not
appropriate to turn the knock and announce requirement “into
a set of sub-rules.” Banks, 540 U.S. at 41. “[A] categorical
scheme on the general reasonableness analysis threatens to
distort the ‘totality of the circumstances’ principle, by replac-
ing a stress on revealing facts with resort to pigeon holes.” Id.
at 42.

                              III.

  Our original opinion did not address Combs’ assertion of
Sixth Amendment error. Because Combs did not challenge his
sentence on Sixth Amendment grounds in the district court,
we grant a “limited remand” pursuant to United States v.
Ameline, No. 02-30326, slip op. at 6368-71 (9th Cir. June 1,
2005) (en banc).

  AFFIRMED AND REMANDED.
