A Cambridge police officer was shot in Central Square yesterday morning while investigating a routine traffic violation.

Parolman James Roscoe Jr. is in fair condition in Cambridge Hospital after doctors yesterday removed a bullet from his right bicep.

Roscoe was patrolling Central Square in a one-man car at 4:29 a.m. when he observed a parked vehicle without a rear license plate on Cross Street.

According to Sergeant Alan Hayes, Roscoe asked the driver for his registration. When he could not produce it, Roscoe told him to get out of the car. The driver then pulled out a pistol and shot Roscoe in the arm.

The man and his female companion were seen driving up Albay Street towards Mass Ave in a 1971 or 1972 beige Chevrolet.

Hayes described the suspect as about 35 years old, a 5-ft., 10-in. man with black hair and a beard, weighing approximately 175 pounds.

The police are now trying to locate a man who told a tollperson on the Tobin Bridge that he witnessed the shooting of a police officer.