DALE CITY, Va. (AP) _ A Prince William County police officer and an unidentified gunman were killed early today in a shootout outside a Dale City home.

Officer Philip Michael Pennington was a member of the Prince William police SWAT team sent to the home to investigate the wounding of an Arlington County deputy earlier Thursday, a Prince William County police spokesman said.

SWAT team members and Arlington police converged on the house about 6:30 a.m., spokesman Sgt. Barry Bernard said.

''At that time there was an exchange of gunfire. As a result of that we had one Prince William County police officer who is dead. We also have an unidentified male dead at the scene,'' Bernard said.

Arlington County police spokesman Tom Bell said the officers were trying to serve an arrest warrant for the shooting of Arlington County Sheriff's Capt. Daryl Laclair.

Laclair, 36 and a 10-year veteran, was shot in the face and left elbow as he approached a car on a busy county highway shortly after midnight Thursday, Bell said.

''A motorist pulled beside him in the left lane and motioned for him to stop. After pulling over, he was proceeding toward the car and the motorist got out and fired three shots,'' Bell said.

The wounded Laclair shot out the rear window of the motorists' gold Buick as the car sped away, Bell said. Laclair was admitted to Arlington Hospital, where he was listed in satisfactory condition.

A witness reported the Buick's license number to police, who traced it to the Dale City home, Bell said.