NEW YORK (AP) _ A police officer is charged with assault for firing five shots at an armed, black undercover colleague he mistook for a gunman on a crowded subway platform.

Officer Peter DelDebbio surrendered to authorities early today after an indictment was unsealed and was charged with two counts of assault in the shooting of Officer Desmond Robinson, said Manhattan District Attorney Robert Morgenthau.

``At least one (shot) was fired when Robinson was virtually on the ground, and some were fired as he was falling,'' Morgenthau said. ``The grand jury has found that the shooting was not justified.''

DelDebbio faces up to 15 years in prison if convicted of first-degree assault; he also is charged with second-degree assault.

A black police fraternal organization claimed DelDebbio, who is of Italian and Puerto Rican descent, overreacted because Robinson is black.

``I'm not looking for vengeance,'' Robinson said at a news conference today before the indictment was announced. ``God has been nice to me.''

Asked if he felt sorry for DelDebbio, Robinson said, ``I can't say I would forgive anyone for shooting me in the back.''

DelDebbio said through police union officials representing him that he fired in self-defense while he was off-duty because he ``faced a gun.'' He denied shooting Robinson in the back as he lay on the ground.

The two officers squared off on Aug. 22 while converging on an armed teen-ager in a crowded Manhattan subway station during evening rush-hour. DelDebbio, who was not in uniform as he rode home on a train, fired five shots at close range, critically wounding Robinson, a plainclothes officer whose gun was drawn.

As Robinson recovered, he said DelDebbio had shot him four times in the back _ a contention supported by a private forensic pathologist hired by Robinson's lawyer, Brian O'Dwyer. Robinson said he was struck by two shots while he was face-down and defenseless on the platform.

``Peter DelDebbio defended himself and used proper force,'' said James Lysagt, an attorney for the Patrolmen's Benevolent Association. ``It's an indictment of society.''

The first-degree assault charge carries a sentence of up to 15 years in prison. DelDebbio was also indicted on a charge of second-degree assault, O'Dwyer said.