The officer opened fire after being confronted by a man on a moped in Washington Heights who whipped out a gun about 9:45 p.m. Sunday.

Upon seeing the weapon, the off-duty officer quickly drew his own gun and fired multiple rounds at the suspect.

Investigators believe up to four shooters were involved, and police fear the violence could spark retaliations. The attack marks the city’s second mass shooting in just weeks. FOX 5 NY's Kendall Green has the latest.

Last month, four other former high-ranking NYPD members, including former Chief of Detectives James Essig, sued the NYPD and the mayor over accusations of fraudulent promotions, and Thomas Donlon claimed in a separate suit that he was removed as interim commissioner when he tried to report corruption and misconduct.

An NYPD detective who was working security near the Park Avenue building where a madman killed four people had her good name dragged in the mud in the aftermath of the slaughter.

City & State found uncredentialed psychologists handling the job under a professional licensure exemption that the NYPD argues is valid.