Two people have been killed and up to 17 others injured in a shooting at teenagers' nightclub event in Florida, police say.

Children as young as 12 were believed to have been caught up in the shooting at Club Blu in Fort Myers, about 250 kilometres north-west of Miami.

The Fort Myers Police Department said in a statement the shooting was not an act of terrorism.

Police identified the two dead as Stef'An Strawder, an 18-year-old basketball star at a local high school, and Sean Archilles, 14.

Besides the two fatalities, a local hospital said there were 17 other victims, ranging between ages 12 and 27.

Police put the number of injured at 14 to 16, with their injuries ranging from minor to life-threatening.

The shooting took place in the nightclub parking lot just after 12:30am local time.

Police found "several victims suffering from gunshot wounds", the Fort Myers Police Department said.

Three people have been detained for questioning, police said, and the area was "deemed safe" although roads in the vicinity were closed as the investigation continued.

In a statement on its Facebook page, Club Blu said it was "deeply sorry for all involved".

"There was armed security as well as full security, inside and out. As the club was closing and parents were picking their children up … that's when all this took place," they said.

Local television station WINK News said two other crime scenes nearby were linked to the initial shooting.

A nearby home and vehicles were also shot at, resulting in one minor injury, CBS news reported.

The incident comes six weeks after a gunman fatally shot 49 people wounded 53 others at the Pulse Nightclub in Orlando.

Police killed that gunman, Omar Mateen, a 29-year-old US citizen of Afghan origin, after a three-hour standoff.

That rampage and other recent shootings have renewed debate about gun laws in the United States.

ABC/wires