At least nine people have died after devastating earthquake-like flash floods swept through villages in central Italy on Thursday evening.
Four people are missing after deluges saw 40cm of rain dumped in the Marche region.
Local authorities said they were unprepared for the sudden “water bomb” drop in just two to three hours, which saw cars swept away.
Water submerged the streets of several towns in the region’s capital, Ancona, on the Adriatic coast, and in the provinces of Pesaro-Urbino.
About 300 firefighters are taking part in the rescue efforts, with crews pictured using dinghies to get people to safety as others tried to clear the debris.
Serra Sant’Abbondio town mayor Ludovico Caverni said the showers were “like an earthquake”, state radio RAI reported.
The head of civil protection for the Marche regional government, Stefano Aguzzi, said the rain was much heavier than expected.
“We got a normal rain alert, but no one expected something like this,” he told reporters.
The head of the national civil protection agency, Fabrizio Curcio, travels to Ancona to assess the damage.
Italian police said some villages have been cut off and many roads are closed due to extreme weather conditions, which have left a trail of destruction.
Paola Pino d’Astore, an expert at the Italian Society for Environmental Geology (SIGEA), said the floods were the result of climate change.
“It is an irreversible phenomenon, a taste of what our future will be,” she warned.
Meanwhile, political party leaders campaigning for Italy’s September 25 general election also expressed solidarity with the rescue efforts.
Center-left Democratic Party leader Enrico Letta said he would suspend campaigning in the Marches as a “sign of mourning” and to allow local activists to help flood-affected communities.
Mr Letta tweeted Thursday morning: “Stunned and speechless at the tragedy that has befallen Marche.
“Thinking (of) and crying for the victims.”
He expressed his hope that the rescuers would succeed “in their hard work”.