FORT MYERS, Florida (CNN) -- The two people killed outside a Florida nightclub's teen party were teenagers, Fort Myers police said.
Sean Archilles, 14, and Ste'fan Strawder, 18, were shot to death Monday morning in the parking lot of Club Blu Bar and Grill, police said.
At least 16 others, ages 12 to 27, were wounded in the shooting. Of the four people still hospitalized Monday, two are in critical condition, and two are in fair condition, Lee Memorial Hospital said.
Police said the shooting was not terror-related and detained three adults in relation to it. But many other details remain uncertain.
"Investigators are working very hard to determine a motive," Fort Myers police said in a statement. "The investigation is still very active as is the crime scene."
'Nothing more we could (have) done'
A flier posted on Facebook advertised the club's "Swimsuit Glow Party" Sunday night. It said no identification would be required to enter, meaning the party was open to all ages.
Club Blu released a statement Monday saying it tried to provide a safe environment for teens.
"We are deeply sorry for all involved," the club posted on Facebook.
"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. As the club was closing and parents were picking their children up.....that's when all this took place. There was nothing more we could of done az you see it was not kids at the party that did this despicable act."
Police didn't say how many shots were fired, but the front of the club was covered with at least 36 yellow evidence markers.
"It was chaos. I saw a bunch of people running across the street," nearby resident Jermaine Wilson said. "It's incredible that this can happen at a teenage (event)."
More crime scenes
Police are investigating two other related scenes, one on Ortiz Avenue, where a person of interest has been detained. The other scene is on Parkway Street, where gunshots hit property and a bullet grazed a person, according to CNN affiliate WINK-TV.
But the area is now "deemed safe," a police statement said.
Authorities are searching for any suspects who may still be on the loose.
The Lee County Sheriff's Office stopped a vehicle that had a suspect in it, Mulligan added, but did not give any additional details about the stop.
A previous version of this story incorrectly spelled victim Sean Archilles' name based on an earlier police statement.
CNN's Chuck Johnston reported from Fort Myers, and Holly Yan wrote from Atlanta. CNN's Euan McKirdy, Shawn Nottingham and Christine Sever contributed to this report.