One Colorado police officer has some explaining to do. A group of car thieves also bit off far more than they could chew.

Authorities believe the group went looking for vehicles left outside to warm up early one morning. They stole multiple cars within a 1.5-mile radius in Aurora, Colorado. Around 6 a.m., the suspects drove off with an unmarked police cruiser.

The unmarked patrol car was a take-home vehicle. An Arapahoe County deputy had left it running in a driveway to warm up. Investigators have not said whether the thieves targeted the police car or seized an unexpected opportunity. It’s also unclear whether they realized what they had stolen before it was too late.

After what must have been an awkward call to dispatch, the department moved quickly. Officers tracked down the stolen cruiser and recovered it about 15 minutes later. They also recovered one additional stolen vehicle.

Department launches internal investigation

The sheriff’s office confirmed deputies are allowed to commute in designated take-home vehicles. However, having one stolen—along with police equipment inside—poses a serious security risk.

The department has opened an internal administrative investigation into the deputy who left the vehicle running. Authorities have arrested one suspect. They continue searching for others believed to be involved in the theft spree.