Two children are among the missing, Franceinfo radio reported on Sunday.
On Saturday night, heavy rainfall hit the region, prompting police to begin active search and rescue operations. By Sunday evening, the bodies of two dead people were found in the car.
In addition, a 62-year-old Belgian man died after his car was washed away by the course when he tried to cross a bridge, traffic on which was blocked due to rising water levels.
(With UNI inputs)