SPOKANE, Wash. -- Court documents reveal that a Spokane County Sheriff's deputy had an AR-15 stolen from his patrol car.

The documents show that the deputy's vehicle was parked in front of his home.

During the night of December 7, someone smashed the front passenger side window in his patrol car with a hammer. The person took the deputy's duty bag and his department issued AR-15. Officials said the rifle was in a locked box inside the car.

"This is something that does concern us. It's something we have been trying to address and to have this happen with one of our deputy's vehicles, we definitely understand that this is just not normal," said Spokane Sheriff Office Deputy Mark Gregory. "They are secured in locking mechanisms that are in the vehicles the same as when we're out on patrol. They're not just sitting in a vehicle."

The Sheriff's Office said the gun is left locked in the car in case the deputy gets called out and needs to respond to a scene quickly. Officials are investigating.