The Fairfax City Police Association is offering a $1,000 reward for information leading to the arrest and conviction of the person or persons who fired a shotgun in January at a city police officer working undercover for the Prince William County Police Department.

The officer, who has not been named to protect his identity, was only slightly injured Jan. 2 when a shotgun was fired several times into his car from a passing car on Rte. 1 near Dumfries, Fairfax City deputy police chief Samuel S. Ellis said.

The officer was returning home at about 1:30 a.m. on the virtually deserted four-lane highway when he glanced at a car passing him and saw an open window and shotgun barrel, Ellis said.

The officer slammed on his car's brakes and threw himself on the floor as a gunshot struck his car windows. The gunman's car stopped about 150 feet in front of the officer's car, Ellis said, and more shots were fired. The officer fired several shots at the gunman with his service revolver.

The officer was working on a Prince William drug investigation under a cooperative regional police program organized in 1975 by the Metropolitan Washington Council of Governments, Ellis said.