Two of the three people killed in a bar shooting in the New York City borough of Brooklyn were among the four shooters who opened fire inside the building, the city's police commissioner said Monday.

The widow of the off-duty police officer who was killed in a mass shooting July 28 in New York City's Midtown Manhattan, gave birth to the couple's third child Monday.

Investigators believe one or more individuals opened fire with multiple weapons at the Taste Of The City Lounge in Brooklyn's Crown Heights, following "a dispute" just before 3.30am. New York Police Department commissioner Jessica Tisch confirmed three men were killed.