The gunman entered the club and opened fire hitting people as young as 13 in Club Blu, in Fort Myers in Florida.
Lieutenant Jim Mulligan of Lee County Sheriff's Office confirmed as many as 17 people had been wounded.
The incident happened shortly after 1am at what was described as a 'teen night' by local US sites at the club.
#BREAKING: Report: 15 shot at Fort Myers, Florida nightclub. Via @NBCNews pic.twitter.com/cB5VDlRzsY— Brendon Geoffrion (@tv_brendon) July 25, 2016
Police said that two other scenes are connected with the incident. One involved a house that was shot at where there was one minor injury, police said, and another was where a "person of interest" had been detained in connection with the shooting, authorities said.
Police are still "actively canvassing" the area to look for other people who might be involved in the attack, they said.
Police do not yet understand the motive for the shooting.
Witnesses said the scene was that of a "mad house".
One witness told local media she heard around 30 gunshots and saw teens running through the car park dodging bullets.
Syreeta Gary's daughter survived the attack. Speaking on a Twitter video, she said: "Well, I just thank God that my daughter is okay. She could have been shot. She was dodging bullets and dropping between cars.
"It is ridiculous that kids have to go through this and they cannot enjoy themselves because you have people with criminalistic minds who want to terrorize people.
'I'm just glad that she's okay.
"She was running away from bullets so she wouldn't get shot. Her friend got shot in the leg.
"They were running for safety."