An investigation is under way in France after three bystanders were killed by the rotors of a helicopter which went out of control as it took off from the car park of a restaurant.

A fourth person was injured in the accident near Arles in the southwest of the country.

The incident occurred at the Chez Bob restaurant on a road between Salin-de-Giraud and Arles in the Camargue region.

It is understood two of the dead were decapitated while the injured woman had her leg severed, rescuers said.

All four people on board the helicopter were unhurt. They had been at lunch in the restaurant and a group had gathered to say goodbye as they left on the aircraft.

It is not clear what caused the crash, which occurred shortly after take-off.