Police say the suspect pulled up behind her, shined a bright spotlight on her car and used a loudspeaker system to pull her over.
The victim told investigators the suspect was wearing a dark colored uniform with a badge on his chest.
"He starts asking specific questions about where you were, where you going, and then the subject changes and he starts to get into a more of a sexual explicit type conversation which scared our victim, rightfully so," said Cpl. Rudy Lopez from the West Covina Police Department.
The woman activated her car alarm, scaring the suspect away.
Police say the victim wasn't able to get a good look at the imposter's vehicle because of the bright light.
The suspect is described as a white male in his 40s, with a thick busy brown mustache and muscular build.
Anyone with information is urged to call the West Covina Police Department at (626) 939-8557.
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