Authorities say the shooting was not an act of terror, but what sparked the violence is not yet clear. The shooting happened at Club Blu in Fort Myers, which had hosted a swimsuit-themed party for teens late Sunday night.
The club said on its Facebook page that the shooting broke out as parents came to pick up their children.
The incident happened shortly after 1am at what was described as a 'teen night' by local US sites.
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 have not yet determined a 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 carpark 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 terrorise 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."
The shooting comes more than a month after a nightclub shooting in Orlando that was the deadliest shooting in modern US history.
- With agencies
