BOSTON -- State Police issued a warning for women Monday morning after a man posing as a state police trooper stopped a woman and sexually assaulted her.

NewsCenter 5's Todd Kazakiewich reported that the woman was stopped about 2:15 a.m. Saturday on Route 24 in Randolph by what she thought was an unmarked police cruiser.

"She was ordered out of the car by someone she thought was a police officer and was sexually assaulted on the side of the road by her vehicle," State Police Lt. Eric Anderson said.

Troopers said the man then got into his car and drove away. He was described as being an older white male with a heavy build, weighing about 215 pounds. He had gray hair in a crewcut style and a goatee. He was wearing clothing similar to a police uniform and his car was a large, older-model 1990s vehicle with faded paint.

"The vehicle that was used in the incident ... the individual had one single blue light on the dash and that was the only indication that it was possibly a police vehicle," Anderson said, adding that real unmarked police vehicles have multiple lights.

Anderson said if motorists are suspicious about unmarked vehicles attempting to stop them, they should put their hazard lights on and proceed slowly to a well-lit area where there are other people, such as a police or gas station. He also suggested a call to 911 to confirm that the person stopping you is an officer and advises asking to see a badge or photo ID.

Anyone with information about this suspect, vehicle or incident is asked to contact the State Police Barracks in Milton at 617-698-5840.