A family of four, including two children aged four and 13, was caught in the floods while trying late Saturday evening to drive across a bridge over the river Gardon in the village of Dions, north of the city of Nimes, the prefecture said.

The father and the two children were still missing but the mother, 40, who was also in the car, was found by rescuers and taken to hospital, it added.

In Dions on Sunday a helicopter flew over the village and the bursting waters of the Gardon while large numbers of firefighters engaged in search efforts, helped by drones and dogs. The bridge was still submerged.

Rescuers were also searching for two women, believed to be aged 47 and 50, who made an emergency call on a bridge in the town of Goudargues to the north before contact was lost.

Another driver, of Belgian nationality, was also missing and feared to have been swept away from a bridge in the village of Gagnieres also in the Gard department. The road had been closed and a policeman had told the driver not to drive on the bridge, officials said.

A passenger in his vehicle, also Belgian, managed to get out and take refuge in a tree, before being rescued after more than two hours amid the branches.

In the neighbouring department of Ardeche, the manager of a hydroelectric power station who went to check on the facility has also been missing since Saturday evening in the village of Saint Martin de Valamas. Searches are continuing.

Interior Minister Gerald Darmanin said rescuers had carried out a total of 35 operations as the storm and torrential rains swept across the Ardeche and Gard departments. He added that all the vehicles swept away had been found but there was still "not a trace" of those missing.

The prefecture in the Gard department expressed regret that despite multiple warnings about the incoming storm, "we still see behaviour that is dangerous, first of all for the people themselves but also dangerous for the people whose duty it is to come to their aid."