At least 95 people have been killed in Spain’s worst flooding in decades when a year’s rain fell in just eight hours, sweeping away bridges and buildings and dragging cars and chunks of masonry from buildings.

A churning tide of brown water gushed through streets in the rain-battered eastern region of Valencia, which produces two-thirds of the citrus fruit grown in Spain.

The torrential downpour caused pile-ups on highways and deluged farmland. Residents clambered onto the roofs of cars as streets turned to rivers.

The death toll appeared to be the worst in Europe from flooding since 2021, when at least 185 people died in Germany.

It is the deadliest flood-related disaster in Spain since 1996, when 87 people died near a town in the Pyrenees mountains.

Debris in the flood-hit municipality of Paiporta, in the province of Valencia. Photo: AAP

“It’s a river that came through,” said Denis Hlavaty, who waited for rescue on a ledge in the petrol station where he works in the regional capital.

“The doors were torn away and I spent the night there, surrounded by water that was two metres deep.”

The government declared three days of mourning amid the unimaginable tragedy.

Prime Minister Pedro Sanchez promised to rebuild infrastructure that had been destroyed.

“For those who at this moment are still looking for their loved ones, the whole of Spain weeps with you,” he said in a televised address on Wednesday (local time).

Footage shot by emergency services from a helicopter showed bridges that had collapsed and cars and trucks piled on top of each other on highways between flooded fields outside Valencia.

Trains to Madrid and Barcelona were cancelled due to the flooding, and schools and other essential services were suspended in worst-hit areas, officials said.

Power company i-DE, owned by Europe’s biggest utility, Iberdrola, said about 150,000 clients in Valencia had no electricity.

Emergency services in the region urged citizens to avoid all road travel and to follow further official advice. A military unit specialising in rescue operations was sent to some places to help local emergency workers.

Some parts of Valencia, such as the towns of Turis, Chiva or Bunol, had more than 400 millimetres of rain, leading the state weather agency AEMET to declare a red alert. It was lowered to amber on Wednesday as the rain eased.

Cars were tossed around in the raging waters. Photo: AAP

There was also flooding in other parts of the country, including the southern region of Andalusia. Forecasters warned of more bad weather ahead as the storm moved in a north-east.

The regional weather service in Catalonia issued a red alert for the area around Barcelona, warning of high winds and hail, while the AEMET state agency placed the city of Jerez in Andalusia on red alert.

“[The floodwaters] took away lots of dogs, lots of horses, they took away everything,” said Antonio Carmona, a construction worker and resident of Alora in the southern region.

European Commission President Ursula von der Leyen said on X that Europe was ready to help.

“What we’re seeing in Spain is devastating,” she wrote.

ASAJA, one of Spain’s largest farmer groups, said on Tuesday it expected significant damage to crops.

Spain is the world’s largest exporter of fresh and dried oranges, according to trade data provider the Observatory of Economic Complexity. Valencia accounts for about 60 per cent of the country’s citrus production, according to Valencian Institute of Agriculture Investigations.

Scientists say extreme weather events are becoming more frequent in Europe due to climate change. Meteorologists think the warming of the Mediterranean, which increases water evaporation, has a key role in making torrential rain more severe.

“Events of this type, which used to occur many decades apart, are now becoming more frequent and their destructive capacity is greater,” said Ernesto Rodriguez Camino, senior state meteorologist and a member of the Spanish Meteorological Association.

-with AAP