Two people were killed and as many as 20 - one just 12 years old - wounded when gunfire erupted at a teen swimsuit party at a southwest Florida nightclub early Monday, according to reports.

Sean Achillies, 14, and Stef'an Strawder, 18, were killed in the attack. Strawder, a basketball standout at Lehigh Senior High School, had his dream of playing Division I college ball crushed when he was shot in the right shoulder on his way out of the club, The News-Press reported. He died at Lee Memorial Hospital at 3:30 a.m.

Three "persons of interest" were detained by police, but it's unclear if any are believed to be a shooter. Neither the shooter's identity nor motivation was clear. Authorities have not said if one shooter or multiple shooters were involved. The attack apparently occurred at a teen event billed as a "Swimsuit Glow Party" at Club Blu in Fort Myers, local media reported.

"This was not an act of terror," Interim Fort Myers Police Chief Dennis Eads said on Monday afternoon. "This was not a terrorist act."

The incident appears to have been gang-related, a law enforcement official told Fox News' Matt Dean.

"We are deeply sorry for all involved," Club Blu posted on Facebook on Monday morning. "We tried to give the teens WHAT WE THOUGHT WAS A SAFE PLACE TO HAVE A GOOD TIME. Ages 12-17. There was armed security as well as full security, inside and out."

The area was deemed safe hours later, Fort Myers Police Capt. Jim Mulligan said in a statement. Three people remained hospitalized with serious injuries, local station WINK-TV reported. One of the victims was identified as Cherly Garn, 12, a spokeswoman for Lee Memorial Health System, told WINK.

The shooting came more than a month after a terror attack at a nightclub in Orlando that was the deadliest shooting in modern U.S. history. The shooting at the Pulse nightclub on June 12 left 49 dead and 53 others wounded.

The violence at Club Blu erupted at about 12:30 a.m. Monday, and there were two active crime scenes, Mulligan said. Several hours later a street in the area remained closed as police investigated.

"As the club was closing and parents were picking their children up.....that's when all this took place," Club Blue posted on Facebook. "There was nothing more we could [have] done [as] you see it was not kids at the party that did this despicable act."

The injured were in a variety of conditions, and some were able to drive themselves to a hospital. Others went to the emergency room as passengers in a friends' car or a police car.

Online state records showed the alcohol license for Club Blu was revoked June 7.

The records from the Department of Business and Professional Regulation state that the club's license was revoked due to an incident that occurred a year ago but there were no details available. The same records also showed a complaint was filed in 2014 for "criminal activity" and that the club was given an official notice.

In a statement, authorities said the Fort Myers police and the Lee County Sheriff's Office were "actively canvassing the area looking for other persons who may be involved in this incident."

Florida Gov. Rick Scott said he was cancelling his scheduled events on Monday so that he could meet with officials in Fort Myers.

In a statement, Scott said he's spoken with Fort Myers Mayor Randy Henderson, Lee County Sheriff Mike Scott and Ft. Myers Interim Police Chief Dennis Eads to offer any assistance from the state.

Fox News' Heather Nauert and Matt Dean and The Associated Press contributed to this report.