The shooting occurred just before 7 a.m. at a Brooklyn nightclub on Utica Avenue in Crown Heights.
Authorities said four men were pronounced dead at the scene.
Five with serious injuries were taken to the hospital, New York City Fire Department officials said.
Investigators said the shooting stemmed from a dispute at the club.
Police made no arrests, but recovered two guns from the scene.
The after-hours club called Triple A Aces is a private and social rental space.