Aurora police are looking for a semiautomatic rifle that was stolen from a patrol officer's personal car.A police spokesman said the officer noticed the weapon missing Thursday evening and reported it the following day. The vehicle was not locked. The officer, who lives in South Aurora, has not been identified.Police say the stolen weapon is an AR-15, .223-caliber rifle. In addition to the gun, several magazines with 30-round capacity, and law enforcement grade ammunition was taken."The department is taking this extremely seriously especially given the nature of the weapon," said Aurora police Detective Robert Friel.Friel said the gun's serial number has been entered into a nationwide database as stolen.Investigators are looking into the possibility someone may have been watching the officer since there were no outward signs suggesting that the rifle was in the vehicle.A local gun dealer said he's not surprised by the theft."Crooks will steal anything they can lay their hands on. They'll steal guns from you, they'll steal from the police department," said Bob French, an employee with Dave's Guns in Aurora.The officer faces possible disciplinary action if it's determined any policies were violated.Friel said Aurora Police Department policy states officers are responsible for properly securing weapons to protect them from damage, theft or misuse. Whether or not the officer is disciplined would be considered an internal matter.The AR-15 is sold legally to the public. Aurora officers must undergo 30 additonal hours of training to carry the weapon for work purposes.Anyone with any information about the whereabouts of the weapon is asked to call Aurora police.