BALTIMORE (Reuters) - A policeman and civilian died and five others were wounded in a shooting incident outside a downtown Baltimore bar early on Sunday morning, with friendly fire possibly a factor in the policeman’s death, a police spokesman said.

The officer who died “was attacked by a number of individuals and he withdrew his weapon in his self-defense,” police spokesman Anthony Guglielmi said, adding that independent witnesses had corroborated this.

Police believe that the civilian killed, apparently by the officer’s shot, was one of the attackers, Guglielmi said.

He said the officer was responding to a disorderly disturbance at 1:15 a.m. outside a bar, the Select Lounge.

The officer “went to break up a fight, other individuals went to attack the officer, and ... began assaulting him severely,” Guglielmi said.

He said the fight was between two young women and the attack on the officer came from a group of males after he broke up the fight.

It was possible that when the officer, who was in plain clothes, was defending himself his badge came off his neck, and officers in the vicinity “could have returned fire thinking that an individual was trying to shoot at them,” Guglielmi said.

He said careful checks of the evidence were being made in investigating that possibility.

Police are waiting 24 hours before naming the policeman at the request of his relatives, but have confirmed he was an 8-year veteran in his 30’s.

In addition to the two deaths, four civilians and one police officer were wounded in the incident, Guglielmi said.