A family of four, including two children aged four and 13, was caught in the floods Saturday evening while trying to drive across a bridge evening over the river Gardon at Dions village, north of Nimes, the prefecture said, France 24 reports.
The father and two children were still missing but the mother, 40, who was also in the car, was found by rescuers and taken to hospital, it said.
The body of another victim was found a few hundred metres from where a car with two Belgian passengers was swept away by the raging waters on Saturday evening in Gagnieres, a nearby village in the Gard department.
Authorities said the driver had tried to cross a bridge even after it was closed and a police officer had told him not to attempt the passage.
One of the two passengers aboard managed to escape and was later found clinging to a tree for more than two hours before being rescued, the prefecture told AFP.
More than 300 rescue workers were deployed in the Gard department, where two other bodies were recovered Sunday from a car in the village of Goudargues, reportedly of two women aged 47 and 50, who had been heading for Spain.
In the neighbouring Ardeche department, a hydroelectric power station manager who went to check on the facility has also been missing since Saturday evening in the village of Saint Martin de Valamas.
The search was called off as night fell on Sunday "because the water flow made the situation extremely dangerous", regional firefighting official Thierry Carret said, adding the search would resume Monday.
Interior Minister Gerald Darmanin said rescuers had carried out 35 operations as the storm swept over the Ardeche and Gard departments.
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".
