Flash flooding around the French Riviera has killed at least 16 people, including some trapped in cars, a campsite and a retirement home.

Torrents of muddy water also inundated buildings, roads and railway tracks, disrupting car and train traffic along the Mediterranean coast.

Helicopters patrolled the area and 27,000 homes were without electricity today after the Brague River overflowed its banks and fierce thunderstorms poured more than 6.7ins of rain on the Cannes region in two hours last night, the equivalent of two months of rainfall for the region.

President Francois Hollande said the overall death toll by midday today was 16, with three people still missing. Government officials had given conflicting reports about casualty figures earlier in the day.

"It's not over," Mr Hollande said, visiting the flood-stricken retirement home in the town of Biot and meeting with emergency workers.

He expressed condolences to families of victims and urged residents to remain cautious, especially on the region's roads, many of which remained impassable. He promised aid for residents hit by the flooding and lamented serious damage to local stores and other businesses.

People were found dead in the towns of Cannes, Biot, Golfe-Juan and Mandelieu-la-Napoule in the south-east, the president's office said.

Interior Ministry spokesman Pierre-Henry Brandet said the dead included victims who had been trapped in a parking lot and others at a campsite and a retirement home. The exact circumstances of the deaths were unclear.

Several trains were stopped because of flooded tracks and traffic remained stopped along the Mediterranean coast between Nice and Toulon, according to the SNCF rail authority. Several roads in the region were closed, including those reaching Cannes.

Winds and rain whipped palm trees along the famed Croisette seaside promenade in Cannes in images shown on BFM television.

In nearby Antibes, cars were overturned and roads were slick with mud. The flooding also disrupted a French league soccer match in Nice, forcing the stadium to shut down in the middle of play.

Some criticised authorities for not doing more to prevent flood damage in the region. Hundreds of emergency workers were involved in rescue efforts, helped by clear skies around the region Sunday.

Pope Francis offered his prayers for the victims during his weekly Sunday blessing from St Peter's Square.

"We express our nearness to the hard-hit populations, including with concrete forms of solidarity," he said.

The ANSA news agency said that several trains that were halted by the floods were carrying hundreds of Italian pilgrims to or from the shrine at Lourdes. The Italian group Unitalsi, which transports the sick to the shrine, said all the pilgrims on board were fine.