BOULDER, Colo. -- Two women walking to their car Saturday morning were stopped by a man they thought was a cop. It happened in a parking garage near 11th and Spruce Street.

One of the women told police she was ordered to take a series of sobriety tests. The woman obliged but said she was fondled in the process.

After the fake cop fondled her, he left, she said. He was driving a white unmarked Crown Victoria with flashing blue lights. Police said they received the call somewhere around 3 a.m. and immediately began investigating.

They have determined the man did not work for Boulder police. They also said it was very odd that he was driving a car with blue lights because all "real" cop cars have red and blue flashing lights as mandated by the state.

"It's very concerning. Obviously our officers need people to feel comfortable in their presence," said Sarah Huntley, of Boulder police.

She said right now they are trying to track him down and looking into the possibility of garage surveillance.

There was recently a string of police impersonations in Denver but Huntley said, at this point, there is no way to determine if this incident and Denver's are linked.

Those parked in the garage said the news had them on edge.

"It makes me really nervous to walk to my car actually," said Christen Cooper.

Police said if you are suspicious of an officer, ask to see identification and a badge. All officers, both in and out of uniform, carry it.

Huntley said if you are pulled over by someone you are leary of call 911. Dispatch can tell you if an officer is in your area and send over someone in uniform to assist.

Huntley said the investigation into Saturday's incident is ongoing. If anyone saw this man, you are asked to call Boulder police.