Torrential rains flooded roads and towns on Tuesday, resulting in cars being swept through streets, a train being derailed and damaged houses and buildings.
Authorities in the worst-hit areas had advised people to stay at home and avoid all non-essential travel.
According to state broadcaster TVE, police said at least 13 people have died in the floods affecting southeastern Spain.
Hours earlier, the leader of the Valencia region told reporters that bodies had been found but did not provide a number “out of respect for the families”.
Earlier, the national government office for the Castilla La Mancha region told radio channel Cadena Ser that six people in the region were missing.
In Letur, near the Sierra de Segura, 30 people were trapped after the river running through the town burst its banks.
Dozens of videos shared on social media appeared to show people trapped in floodwaters, several of them hanging on to trees to avoid being swept away. Authorities used helicopters to rescue some residents from their homes.
Other videos shared by Spanish broadcasters showed floodwater rising into the lower levels of homes and even carrying cars through the street.
Radio and TV stations received hundreds of calls for help from people trapped in flooded areas or searching for loved ones, as emergency services were unable to reach all affected locations.
‘It was mayhem’
A British couple told Sky News they had been stuck in their car for almost 10 hours.
Vitalij Farafonov and his wife were visiting Valencia on a yoga retreat when they were diverted by police from a motorway at around 8pm last night.
He said: “It was mayhem as we counted nine or 10 overturned lorries on a half mile stretch of the motorway.
“We’ve never seen anything like it.”
The couple, who are originally from the Midlands but now live in Luxembourg, have four children who are safe in Barcelona with relatives.
Mr Farafonov said he and his wife were stuck “on a random rural road in between what were beautiful orange groves”.
“We can finally see flashing blue lights so people do know where we are,” he added. “As I say, we are the lucky ones.”
Transport was severely affected by the flooding.
A high-speed train with almost 300 people on board was derailed near Malaga, but authorities said no one was hurt.
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Rail lines elsewhere were also disrupted.
Storms are forecast to continue until Thursday, according to the country’s weather service.
Spain has experienced similar autumn storms in recent years.
Scientists have warned that increased episodes of extreme weather, like flash floods, or the wildfires seen elsewhere in Europe in the summer, are likely linked to human-driven climate change.
Meteorologists believe the warming of the Mediterranean, which increases water evaporation, plays a key role in making torrential rains more severe.
