Flooding from record rains in the mountainous region that spans France and Italy has killed two people in Italy and left at least 24 people in the two countries missing.
A storm that moved overnight across south-eastern France and then northern Italy caused major flooding on both sides of the border, destroying bridges, blocking roads and isolating communities.
In Italy, a firefighter was killed during a rescue operation in the mountainous northern region of Val d’Aosta.
Another body was found in Vercelli province, near where a man had been swept away by floodwaters late on Friday.
24.8in The amount of rain that fell in a 24-hour period in Piedmont region
A total of 16 people were reported missing in Italy, all but one travellers in cars on the Col de Tende high mountain pass between France and Italy, according to civil protection authorities.
They include two people from Germany driving with their 11-year-old and six-year-old grandchildren, and a pair of brothers returning from France.
The spokesman for Italy’s firefighters said a search was ongoing for a missing shepherd who was pulled into floodwaters on Col de Tende.
His brother managed to grab on to a tree and was saved, while authorities were searching on the French side for the shepherd.
Firefighter spokesman Luca Cari said he suspects the other people reported missing in Italy have lost phone contact, but at the moment they are not thought to be in imminent danger.
The situation at the tunnel on the high mountain pass is complicated by the fact that French emergency responders cannot access their side due to flood damage, Mr Cari said.
Italian firefighters were searching the French side for people who may have been blocked.
Unrelenting rainfall overnight hit levels not seen since 1958 in northern Italy’s Piedmont region, where as much as 630 millimetres (24.8in) of rain fell in a 24-hour period, according to the Italian civil protection agency.
Hundreds of rescue operations were under way.
Eleven campers were saved in Vercelli province, where floodwaters hit 20-year highs.
And Alpine rescue squads have evacuated by foot seven people who were in houses cut off by flooding at Terme di Valdieri; some had to be carried on stretchers due to the muddy conditions and accumulation of detritus.
On the other side of the border, in south-eastern France, almost a year’s average rainfall fell in less than 12 hours in the mountainous area surrounding the city of Nice.
Local firefighters said at least eight people were missing, including two firefighters whose vehicle was carried away by water when the road collapsed during a rescue operation.
Nice mayor Christian Estrosi expressed his “emotion and sympathy” for the families.
He said more than 100 homes have been destroyed or severely damaged.
Firefighters said several dozen people were evacuated from their homes overnight.
French President Emmanuel Macron on Saturday expressed gratitude towards rescuers on Twitter.
“Together we will get through this,” he said.
France’s national weather agency, Meteo France, said that up to 500 millimetres of rain (19.7in) were recorded in some areas, the equivalent of almost one year of average rainfall.
Meteo France had issued a danger alert on Friday and all schools in the region had been closed.
Local authorities urged people to stay at home.
French prime minister Jean Castex and interior minister Gerald Darmanin arrived in the area later.