Some 36 injured were taken to hospital following the accident near Verona on Friday night, which occurred when the vehicle struck a pylon and burst into flames, according to emergency workers.
The French bus driver, together with his family, could be among the victims, Italian news agency Agi said.
The bus was carrying around 50 passengers, most of whom were Hungarians aged between 16 and 18, firefighters said.
Agi also reported that the bus was returning from a school trip to France.
Police are awaiting the go-ahead from the prosecutor to analyse the charred remains of the bus.