Mesquite police say a phony police officer tried to pull over an off-duty officer on Monday night.

A man in a white Crown Victoria tried to pull over the real officer on Interstate 635 near La Prada Drive shortly after 9:30 p.m., police said.

The real officer pulled over and waited for the impostor, but the driver took off instead. The officer followed him and called 911, but the driver got away. The car was last seen in the area of Buckner Boulevard and Chenault Street in East Dallas.

The impostor's red, orange and yellow flashing lights emanated from inside the vehicle and were not exterior emergency lights. But there's one dead giveaway to look for when you see flashing lights, police said.

"Most police agencies throughout the state of Texas will display red and blue lights to the front," Garland police spokeswoman Officer Joe Harn said.

Some police officers drive unmarked vehicles. But if you aren't sure if a car is a legitimate police vehicle, police advise calling 911.

"It is very easy to call 911 ... and find out if it is a real police officer, and you can request another officer to come there to verify that," Harn said.

The police impostor in Monday's incident was in an older model white Ford Crown Victoria with temporary tags and no wheel covers. It did not have markings or insignia.