At least 19 people have been killed by flash floods in south-eastern France, officials say.
Several others have been reported missing after torrential rain hit the mountains above the Cote D'Azur region on Tuesday.
A number of towns in the department of Var were affected, with hundreds of homes flooded.
Meteo France, the national weather service, said up to 40cm (15.7in) of rain had fallen since Tuesday.
Meterologists say the floods are the worst in the region since 1827.
About 2,000 rescue workers have been drafted into affected regions around Draguignan - the worst-hit area - near the Mediterranean coast to help those trapped in their vehicles or houses.
Water levels were said to be falling slightly in Draguignan on Wednesday, though the rain was continuing in nearby Roquebrune and Frejus.
Meteo France has warned of further storms on Wednesday night.
"We have never seen so much rain in the month of June," Patrick Galois of Meteo France told the AFP news agency.
At least 1,000 people had to leave their homes and spend the night in schools or other temporary shelters, and some 175,000 houses were estimated to have been left without electricity.
Some reportedly sought shelter on the roofs of their homes, while helicopters were brought in to rescue people.
Rescue teams had to moved 436 inmates from a prison in Draguignan after two floors flooded.
The force of the water swept empty cars and other vehicles down streets in Draguignan.
"This morning, we woke up to find a town centre that was devastated, extremely battered with overturned cars floating in the streets, collapsed roads and gutted houses," said Corinne Orzechowski, the official leading the emergency operation.
The BBC's Hugh Schofield in Paris says that many of those who died were caught in their cars.
Rail and air services in the region were interrupted, and about 300 passengers travelling on a high-speed train between Nice and Lille had been trapped by the flood waters, the AFP news agency reported.
The railway line between Toulon and Frejus will be closed until Thursday morning.
President Nicolas Sarkozy offered condolences to the families of the victims, and pledged his support to rescue workers "mobilising non-stop to provide aid and find those still missing".
He plans to visit the area early next week.