A surviving victim is hospitalized on life support.
A new search at the scene began at first light after investigators learned that one person in the crashed vehicle was unaccounted for.
"It's believed there may possibly be a fourth person," Florida Highway Patrol Sgt. Mark Wysocky said Thursday morning.
Wysocky said the crash happened shortly after 10 p.m. Wednesday just south of Hillsboro Boulevard and involved three vehicles.
"As a result of that crash, one of those vehicles ran off the road, through the fence and into the lake," he said.
Broward Sheriff Fire Rescue Deerfield Beach crews and BSO Marine Unit divers combined efforts at the scene to get the occupants out of the submerged SUV.
"Three young adults, two females and a male, were taken by Broward Sheriff Fire Rescue units to Broward Health North," said agency spokesman Mike Jachles.
On Thursday morning, Wysocky identified those who died as: Nadege Theodore, 37, of Pompano Beach, the driver of the SUV and Guivens Daverman, 16, of Pompano Beach.
Sandalie Jean-Baptiste, 20, was at Broward Health North on life support, Wysocky said.
The identity of the person recovered from the water Thursday morning was not immediately disclosed, but Wysocky earlier said a 15-year-old girl was unaccounted for after the crash.
The crash happened as Theodore and the others were on their way back from the Town Center at Boca Raton mall.
Information about the possible fourth victim came to light as family members of those involved in the crash were being notified.
"We made next of kin notification and they advised that another person might be missing," Wysocky said.
The cause of the crash remains under investigation.
This developing story will be updated as soon as additional information is available.