Police are still investigating Wednesday night's deadly shooting at the Irving Plaza concert hall near Union Square.
Shots rang out around 10 p.m. as hip-hop star T.I. was getting ready to perform.
Police say a fight broke out in a green room area on the third floor, and someone pulled out a gun.
33-year-old Ronald McPhatter was shot in the stomach and later died, according to police.
The Brooklyn rapper Troy Ave was shot in the leg, along with another man and a woman, according to the police report.
They were all taken to the hospital.
"The show was about to start, and like literally in the midst of the concert I heard two pops myself, and then right after that there was a whole stampede of everyone trying to rush out of the auditorium together, so yeah, insane," one concert goer said.
Police said they are looking into how the shooter managed to bring a gun into the venue.
"There was metal detection there, there was a security force there. We're trying to determine if anybody defeated that. But sometimes they come in with things — we don't know yet," NYPD Chief of Detectives Robert Boyce said at a press conference. "So we'll go forward with that part of the investigation — had there been adequate security there."
"Detectives are still interviewing potential witnesses, canvassing for video and looking for cameras in the area that can help us identify people that were there that witnessed this scene," said NYPD Chief William Aubry.
Sources say some of the rappers had an ongoing dispute.
Police said T.I. — whose real name is Clifford Joseph Harris Jr. — was not hurt and had no part in the incident.
His representatives had no comment about the shooting.