Powerful, rapid-fire assault rifles like the AK-47s used in Third World conflicts are increasingly being used in American street fights.

And many cities, from Miami to Minneapolis to Farmington, have issued these semiautomatic rifles to patrol officers to protect themselves and the public.

"We're in an arms race," said Chaska Police Chief Scott Knight, who is chairman of the firearms committee of the International Association of Chiefs of Police. He has ordered 10 AR-15 assault rifles for his officers who, like those elsewhere, have encountered more criminals with high-powered weapons.

Government figures show a marked increase in AK-type weapons traced after they were seized or connected to a crime.

The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATFE) traced the weapons and entered them into the agency's database. The Associated Press obtained the figures through public records requests.

Police SWAT teams were the first equipped with assault rifles. Patrol officers started getting them after the country watched in horror in 1997 as televised footage showed Los Angeles officers fleeing from two bank robbers spraying bullets from assault rifles at a North Hollywood bank. Police handgun shots bounced off the robbers' body armor. Seven civilians and 11 officers were wounded.

More recently, a Miami-Dade, Fla., officer was killed during a traffic stop last September and three other officers wounded by a driver firing an assault rifle. The cops had only handguns.

Last weekend Chaska police stopped a driver who had illegal drugs, a .45-caliber semiautomatic handgun under his seat and a bulletproof vest in his trunk, Knight said. In another recent example, Chaska officers responding to a domestic assault call found an assault rifle in the hands of a man high on drugs. And about three years ago, they encountered a gang member with a MAC-10 handheld submachine gun.

"There is no escaping the fact that these type of weapons are showing up more and more across the country in incidents where multiple innocent citizens and police officers are being gunned down," Knight said. "I want my officers to have the upper hand."

Weapons, by the numbers

The number of assault rifle entries in the ATFE database rose even while the federal assault weapons ban was in effect and has continued to climb since the ban expired in 2004, allowing people to legally buy the rapid-fire weapons.

Since 1993, the year before the ban took effect, the federal agency has recorded a more than sevenfold increase in assault guns -- including the original Russian-made AK-47 and a variety of copycats from around the world. The number of AK-type guns rose from 1,140 in 1993 to 8,547 last year.

Since 2005, the first full year after the ban's expiration, the ATFE has recorded an 11 percent increase in assault weapons.

The agency says the increases in the first half of the 1990s were partly the result of wider use of its weapons database by local law enforcement agencies.

Minneapolis, St. Paul and many Twin Cities suburbs started replacing shotguns with assault rifles about five years ago, police officials said. St. Paul officers used them last year while chasing a suspect who fired at them and then killed himself, spokesman Tom Walsh said.

In early 2004, two officers in the northern suburb of Ramsey fired high-powered rifles at a pickup driven by a mentally ill man. He had shot out a squad windshield and later drove at officers while holding a shotgun out the pickup window, said Chief Jim Way. No one was injured.

Farmington Chief Brian Lindquist said his officers have found assault rifles in vehicles. People can buy cheaper models of the powerful weapons for a few hundred dollars on the Internet, he noted.

The 10 assault rifles that Knight ordered for the Chaska force cost $900 a piece, including a car lock rack. Officers will carry two 30-bullet clips.

The Minnesota State Patrol started phasing in assault rifles about a decade ago and upgraded them three years ago, said Lt. Mark Peterson. The weapon came in handy for a state trooper who responded to a call in East Grand Forks in October 2006. A camouflage-clad man sprayed bullets at local police, who only had handguns, two blocks from a high school and a local college.

When trooper Sgt. Dean Smith ordered the man to drop his weapons, he opened fire, hitting a dumpster protecting Smith. The trooper returned three shots, hitting the man in the hip. He dragged himself behind a wall and shot himself, patrol records said.

"The change from shotguns to [assault] rifles is becoming much more common throughout law enforcement because law enforcement is getting outgunned by crooks," said Dave Bellows, chief deputy sheriff in Dakota County. He said he supervised the change for the county in about 2000 and, before that, for Lakeville police when he worked on the force.

Not only are police seeing more assault weapons, they also see more bad guys wearing body armor, which stops slugs from less powerful guns.

"Crooks are getting much more sophisticated in what they are wearing and the weapons they are carrying," Bellows said. "Law enforcement can't adequately protect society if we can't adequately protect ourselves."

The Associated Press contributed to this report. Jim Adams • 612-673-7658