Nine people died and thousands were evacuated from their homes as torrential rain battered Italy's northern Emilia-Romagna region, triggering floods and landslides, officials said on Wednesday.
Civil Protection Minister Nello Musumeci said some areas had received half their average annual rainfall in just 36 hours, causing rivers to burst their banks, sending water cascading through towns and submerging thousands of acres of farmland.
Sunday's Formula One Grand Prix in Imola, which is close to many of the worst-hit areas, was called off in an effort to relieve pressure on emergency services and prevent motor racing fans from converging on the inundated region.
"We are facing catastrophic events that have probably not been seen before," the president of the Emilia-Romagna region Stefano Bonaccini told reporters. "Extraordinary amounts of rain have fallen on land no longer capable of absorbing them."
The Adriatic coastal city of Ravenna, famed for its early Christian heritage sites, was badly affected. The local interior ministry representative said some 14,000 people would have to be evacuated from the area as soon as possible.
Authorities said flooding had hit 37 towns and communities and around 120 landslides had been registered. At least one bridge, near the city of Bologna, collapsed, some roads were undermined by floodwaters and many rail services were suspended.
Nine bodies had been retrieved from various locations, Bonaccini said. Irene Priolo, vice president of the region, told reporters that although the rains were easing, river levels were still rising.
Civil Protection Minister Musumeci said he would ask the cabinet to find 20 million euros ($22 million) for the affected area when it meets on May 23 to consider relief measures.
Government officials said tax and mortgage payments would be suspended for flood-hit regions during the emergency.
It was the second time this month that Emilia-Romagna has been battered by bad weather, with at least two people dying during storms at the beginning of May.
The torrential rain months of drought which had dried out the land, reducing its capacity to absorb water and worsening the impact of the floods, meteorologists said.
Muddy waters flowed through the historic centres of Faenza, Cesena and Forli, washing over the roofs of parked cars, submerging some stores and forcing locals to flee to the top stories of their homes.
Drone footage from the Imola race circuit showed part of the paddock area under water. Organisers said the decision to call off the Grand Prix had been taken "because it is not possible to safely hold the event for our fans, the teams and our personnel".
"It's probably been the worst night in the history of Romagna," Ravenna Mayor Michele de Pascale told RAI public radio, saying 5,000 people were evacuated from his city on Tuesday night.
"Ravenna is unrecognisable after the damage it has suffered."
Minister Musumeci said between 200mm to 500mm of rain fell in some parts of the region in 1-1/2 days, compared with average annual rainfall of 1,000 mm.