Four men were killed and three people were wounded when gunshots rang out inside a private club in Brooklyn—where police believe there was illegal gambling taking place—shortly after daylight Saturday morning, authorities said.

Three people, two men and a woman, were taken to a local hospital with gunshot wounds that were considered serious but not life threatening injuries, authorities said. A fourth person suffered a leg injury while fleeing the chaos.

The four men who were killed inside what authorities described as a small, “sparsely decorated” room, range in age from 32 to 48, a senior law enforcement official told The Daily Beast. Three of the men each died from a single gunshot wound to the head, the official said, adding that the fourth suffered wounds to the torso and arm.

The shooting took place around 6:55 a.m. Saturday morning at Triple A. Aces, a gathering spot that bills itself as “private & social rental place.”

The place is not licensed to serve alcohol and appears to be is an “illegal gambling location,” NYPD Chief of Detectives Dermot Shea said. “What we see is evidence of some gambling, specifically card, specifically dice,” he said.

Police recovered two guns—a 9mm handgun and a revolver—from the scene and had taken multiple people into custody for questioning as they were working to piece together what happened, authorities said.

“It’s a little preliminary to make speculation whether it’s a dispute, whether it’s a gambling dispute, whether it’s a robbery, but that will unfold as the day goes on,” Shea said. He said there was nothing to indicate the shooting was gang related.

There is evidence of at least 15 shots fired, all inside the club, Shea said. Based on camera footage and interviews, roughly a dozen people were inside the club at the time of the shooting.

The officers who responded had just finished making a gun arrest nearby, Shea said.

The club, which is located three blocks from the local NYPD police precinct, has had no previous encounters with police, said NYPD Chief of Patrol Rodney Harrison.

The three people who injured in the shooting include a 49-year-old man who was shot in right arm, a 35-year-old man who was shot in the leg and a 38-year-old woman who was shot in the leg.

This story is developing.