Communications to the region one of the wealthiest in France, and a magnet for visitors from around the world  were badly hit and thousands of residents were left without power.
President Francois Hollande visited the region, expressing the 'solidarity of the nation' to those affected but also warning that the disaster suggested an environmental message had to be learnt.
"There have always been always catastrophes. But their rhythm and intensity are on the increase," he said, urging that environmental 'decisions be taken' as France prepares to host UN-led climate talks in December on a post-2020 pact to curb greenhouse gases.
Three people died when water engulfed a retirement home at Biot near Antibes, and three drowned when their car was trapped by rising waters in a small tunnel at Vallauris-Golfe-Juan.

Rescue teams at Mandelieu-la-Napoule said the water was so murky that it hampered the search for further bodies in underground car parks, where at least seven people died.
The storm "did serious damage to the railway infrastructure, tracks, crossings, electrical lines, primarily around the area of Cannes," a spokesman for French rail company SNCF said.

Around 15,000 homes remained without power after initially 27,000 residences suffered outages affecting some 700,000 people, network authorities said.


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