Police say two of the men and the woman were shot in the leg in the fracas at SOB's on Varick Street shortly after midnight. The fourth victim was grazed by a bullet, but it wasn't clear where he was hit.
According to The New York Post, the mayhem ensued after a gang member from New Jersey insulted New York City during a mixtape party for Washington, D.C.-based artist Fat Trel.
Witnesses described a stampede as club-goers rushed for the exits when bullets started flying, the paper reported.
Fat Trel tweeted about the chaos, saying, "The inside of my show jus got shut up in NYC!!!!"
The club, founded in 1982 under the name Sounds of Brazil, existed first as a world music venue and later expanded to include R&B and hip-hop. It has hosted artists including Kanye West, Common, Drake, Tito Puente and Marc Anthony.
All of the victims are expected to be OK.
No arrests have been made.