An investigation has been opened to determine the cause of the crash close to the village of Gonfaron in the Var department of southern France on Saturday, regional prosecutor Patrice Camberou told AFP.
According to the French army's southern command, two of the three victims were soldiers from the nearby 2nd combat helicopter regiment training base.
Local firefighters said earlier they had been called out for an aircraft accident that had caused a fire in the surrounding vegetation that was quickly extinguished.
The stricken aircraft was located with the help of water-bombing helicopters, the fire service said.
AMK/PR