Police Lt. Vincent Testa displays weapons recovered after the shooting of Officer Kevin Livewell. Deputy Police Commissioner Richard Ross said the collection of arms was "absolutely scary." (Peter Mucha / Staff)

Police recovered a "scary" arsenal of semiautomatic weapons at the scene where an officer was shot Thursday night in Kensington, authorities said Friday.

Officer Kevin Livewell, 30, was recovering at Temple University Hospital and over the weekend is expected to undergo surgery on his right leg. He was shot just below the knee.

Police had one man in custody Friday and were seeking two others the shooting. The Fraternal Order of Police offered a $5,000 reward for each wanted man.

Gunfire erupted after Livewell and his partner stopped a white van in the 3000 block of North Water Street, police said. Men with assault-type weapons immediately fired four times at the two officers, striking Livewell once, police said.

The man in custody, believed to have been the driver, was tackled by Livewell's partner. Detectives had not charged the man Friday night and declined to identify him.

"We're not putting anything out," a police spokeswoman said, adding that investigators would not release the van driver's name until the other two men were in custody. Homicide detectives were running the investigation.

Deputy Police Commissioner Richard Ross described the collection of weapons recovered at the scene as "absolutely scary."

The fleeing men dropped two assault rifles - an AK-47 and an SKS carbine - as well as a Glock pistol. Inside the van were two Bushmaster AR-15 assault-type rifles, a TEC-9 semiautomatic pistol, a Taurus PT24 pistol, and another Glock.

Except for the Glocks, the weapons can fire bullets "capable of slicing through a vehicle" or piercing armor, Ross said.

"We don't know what they intended to do, but it was no good," Police Commissioner Charles H. Ramsey said. "To have this kind of armament is an indication they intended to harm someone."

Ramsey pointed out that an SKS carbine was used to kill police Sgt. Stephen Liczbinski in May 2008. Two men are on trial in his death.

All of the guns are legal to purchase in Pennsylvania, said Lt. Vincent Testa, head of the firearms investigation unit.

The officers were acting on "information" in pulling the van over, Ramsey said. He declined to confirm a report that the stop was related to an earlier incident.

"We don't know if there's any connection to any other shooting that might have taken place," he said.

Livewell, a nine-year veteran of the department, is married and has a 15-year-old daughter and an 8-month-old son.

Ramsey visited Livewell at the hospital and said he was "in good spirits and doing well."