Local police said the plane had taken off from Belgium and was headed to Switzerland. All four occupants were Swiss.

Rescuers found wreckage of the plane about 40 minutes after it sent a distress call. There was no immediate sign of survivors.

Local mayor Didier Grillot said several witnesses had told him the plane was struck by lightning.

“There’s nothing but a mass of debris, the plane was torn to pieces,” he said after visiting the crash site.