Someone breaking into cars in Stillwater stole a semiautomatic rifle, body armor vest and other items from a federal agent's unmarked car parked in his driveway, police said.

About $4,000 of equipment was taken from the agent's car, including the .223 caliber rifle, about 100 rounds of ammunition, binoculars, a digital camera, GPS units and a Sony recorder, Stillwater Sgt. Jeff Stender said. The rifle was locked to a ceiling gun rack, which the thieves ripped out of the car.

Items were also taken from three family vehicles in the driveway in the 1900 block of Oak Glen Lane.

"It's pretty brazen," Stender said. He said area police have dealt with a rash of car thefts for more than a year and suspect the thieves may be area teenagers who didn't know they could be looking at serious federal charges for taking a rifle from a federal agent.

"We have no reason to believe it is anything else," he said.

"Usually the thief leaves weapons alone. It kind of raises the stakes a little bit. ... We want the rifle back. We are very concerned that it is on the street."

He wouldn't identify which agency is involved, but said it is not the FBI or Drug Enforcement Administration. He said the agent serves several states and works out of his car.