One person has now been confirmed dead in Brittany - a cyclist who fell off his bike after a branch was knocked down by the storm winds in Brest.
The prefecture confirmed that the cyclist was killed instantly, but did not release - for the moment - any more details about the victim.
Firefighters in Alpes-Maritimes said they had been called more than 380 times overnight on Friday to Saturday (October 2-3), while there were 80 call-outs due to falling trees in Brittany the night before.
A total of 10 people across France are still being searched for, and eight others have been declared missing in the aftermath of the storm - as of Sunday morning - with two firefighters among those missing.
A video created by news service FranceInfo shows the further extent of the devastation (below, with commentary in French).
Prime Minister Jean Castex has already visited the Alpes-Maritimes in the wake of the disaster. He said: “I have already begun the procedure for a catastrophe naturelle (natural disaster), so that ministers and the President of the Republic can declare it next Wednesday.”
An official declaration of a “catastrophe naturelle” means that people affected by the disaster are more likely to be able to claim for damages on their insurance.
Mr Castex also said that he would be sending in military backup to help emergency services cope.
He tweeted: "Words are not enough to describe the courage, devotion, and professionalism of our security forces and emergency services putting their lives in danger. I have told them, from all of us, our recognition and our immense gratitude."
Emergency services rescued 21 of the 22 people reported missing by the Italian authorities, near the Col de Tende mountain pass on the French-Italian border. Helicopters were deployed to help them, with those rescued including two German nationals and their Italian grandchildren.
Mayor of Nice, Christian Estrosi, said: “One hundred houses have been swept away or partially destroyed or damaged. It is a disaster the likes of which I have never seen. I want to offer all my thoughts, my sympathy and empathy to all the families [affected]. All services are engaged [to help].”
Alexandra Valetta-Ardisson, MP in the Alpes-Maritimes, said that several towns had lost power and communications, and were cut off. She said: “[This is an] extremely worrying situation. We have gendarmerie units that are no longer reachable in the Tende and Breil sectors.”
Eric Ciotti, MP in the Alpes-Maritimes, tweeted a video taken from a helicopter doing a reconnaissance of damage in the department, over Saint-Martin-Vésubie. He said: “Several dozen houses have been washed away.”
Je survole actuellement avec @ca_ginesy et le colonel Riquier les zones sinistrées par les intempéries d’hier dans les #AlpesMaritimes— Eric Ciotti (@ECiotti) October 3, 2020
Situation terrifiante plusieurs dizaines de maisons ont été emportées! pic.twitter.com/5gJT5CboEA
Charles-Ange Ginésy, president of the department council, was in the same helicopter. He tweeted a video of Roquebillière and said: “My thoughts are with all the emergency services involved and the families affected.”
Je survole avec @ECiotti et le colonel Riquier les zones sinistrées des #AlpesMaritimes.— Charles Ange Ginesy (@ca_ginesy) October 3, 2020
Des images terribles. D’importants moyens aériens, humains et matériels sont mis en place. Mes pensées vont vers les forces de secours mobilisées et les familles touchées. pic.twitter.com/6jOsoIxSfu
According to Météo France, Storm Alex dropped record rainfall on the region, with “more than 500mm” falling “in just a few hours”, which is “almost a year’s worth of rainfall in 10 hours”.
The high level of rain and water is one of the major factors in the extent of the damage, with roads cut off and buildings destroyed by mudslides and the power of the rising water.
Extreme rainfall in south east France is leading to extremely dangerous conditions right now.— Scott From Scotland (@ScottDuncanWX) October 2, 2020
The bridge collapses with what looks like power surge/explosion.#stormalex #tempeteALEX #AlpesMaritimespic.twitter.com/dqStdhCnKB
A firefighter spokesperson said: “Villages such as Saint-Martin-Vésubie and Roquebillière are cut off. There are also some houses that are perched over an empty space because the river washed away the road.”
In more positive news: One gendarme who was reported missing and feared dead has now been found “safe and sound”, in news that is “a real relief”, said Mr Estrosi.
Quel bonheur de revoir l'adjudant de @Gendarmerie Morales après sa disparition hier soir dans les intempéries de la #TempeteAlex et la nuit d'angoisse qui a suivi. Un vrai soulagement de le retrouver sain et sauf. pic.twitter.com/0rNLzipFUB— Christian Estrosi (@cestrosi) October 3, 2020