Authorities said none of the planes' passengers survived in the midair collision at DeLand Municipal Airport, about 25 miles west of Daytona Beach.
The two planes ran into each other and the wreckage of one of the planes went into a pond, according to a police department employee, who refused to identify herself.
"There were no survivors," she said, adding she did not know how many people were aboard the two aircraft.
Police confirmed at least two dead in the crash. Two more people may have been killed, but officials were unable to reach the wreckage immediately in the marshy area to recover the victims.
One plane, a Piper Seminole, was owned by Embry-Riddle Aeronautical University. The other, a Piper Cadet, was owned by Phoenix East, an aviation school. Both schools use the airport for training sessions.
The student and instructor aboard the Embry-Riddle plane were killed, said Lisa Ledewitz, spokeswoman for the school. Their names were being withheld until their relatives were notified.
Ledewitz did not have information about the occupants of the other plane. A spokeswoman for Phoenix East said the flight school would not comment until it had more information about the accident.
The Daytona Beach News-Journal says the two planes hit each other in the air near the end of one runway at the DeLand airport. It says wreckage showered down along U.S. Highway 92 and nearby Marsh Road.