An off-duty New York policeman is dead after he was shot to death by a fellow cop who reportedly mistook him as a gun-wielding criminal.

Omar J. Edwards, of Brooklyn, was chasing a man on East Harlem's 125th Street late Thursday when three officers in a car spotted him with his gun drawn. It's not clear how, or if, the fellow cops identified themselves, or whether Edwards told them he was a policeman before he was shot in the arm and chest.

Andrew Dunston, a four-year veteran from Long Island, is reported to have fired the fatal shots.

Edwards wasn't wearing a bullet-proof vest because he was off-duty. Upon ending his shift, Edwards reportedly found a man rummaging through his car's contents, which led to the chase. But Edwards' identity wasn't learned until the other cops ripped open his bloody clothes to try and revive him -- only to discover the police academy t-shirt he wore underneath.

An investigation has begun, along with criticism of NYPD procedure, and questions of race: Edwards, a 25-year-old Black man, was killed by a White cop. Would Dunston have fired on a White man under similar circumstances?

Mayor Michael Bloomberg called the shooting a "tragedy." Recently married, Edwards was the father of two.