People look at La Nartuby river at a bridge crossing after heavy flooding in Trans en Provence, France on Wednesday. (Sebastien Nogier/Reuters)

Authorities in southeast France say at least 19 people have been killed and 12 are missing in the aftermath of flash floods that followed powerful rainstorms.

Unusually heavy rains in the Var region have transformed streets into muddy rivers that swept up trees, cars and other objects and French meteorological officials are calling for more rain for the region overnight Wednesday.

Workers in boats and a dozen helicopters scrambled Tuesday night to evacuate residents trapped on rooftops by the floodwaters, which reached about 2 metres high in some areas. Other residents swam to safety.

A resident of Draguignan is evacuated by rescue workers from a flooded home in southeast France on Wednesday after rising water from unusually heavy rains hit the region and caused a river to overflow. (Sebastien Nogier/Reuters)

"The windows exploded, the garage door was blocked," a woman from the village of Le Muy, told French radio. "We panicked. We had to swim to nearby buildings to save ourselves, because we couldn't reach the ground anymore. With my son in our arms. He didn't understand what was going on. We had to grab him from his bed."

About 1,200 people spent the night in shelters and 200,000 homes were still without electricity on Wednesday afternoon, the Var government said. Schools in the region were closed and train service ground to a halt in the affected areas.

French President Nicolas Sarkozy sent condolences to the region's residents and thanked the emergency response personnel for their response to the flood.

With files from The Associated Press