An arts and science centre that normally plays host to opera performances was transformed on Saturday into the nerve centre for a massive cleanup operation after catastrophic floods this week in eastern Spain claimed at least 207 lives.

Volunteers went to Valencia's City of Arts and Sciences for the first co-ordinated cleanup organized by regional authorities.

On Friday, the mass spontaneous arrival of volunteers complicated access for professional emergency workers to some areas, prompting authorities to devise a plan on how and where to deploy them.

Carlos Mazon, Valencian regional president, posted on X on Friday: "Tomorrow, Saturday, at 7 in the morning, together with the Volunteer Platform, we will launch the volunteer centre to better organize, (and) transport the help of those who are helping from the City of Arts and Sciences in Valencia."

Spain is also sending 5,000 more soldiers and 5,000 more police to the region of Valencia, Prime Minister Pedro Sanchez announced Saturday, amid mounting criticism over the government's response to the flooding.

Some 2,000 soldiers have already been deployed to search for dozens of people who are still missing and help survivors of the storm, which triggered a new weather alert in the Balearic Islands, Catalonia and Valencia, where rains are expected to continue during the weekend.

In some of the worst-hit areas, people have resorted to looting because they have no food or water. Police said on Friday they had arrested 27 people for robbing shops and offices in the Valencia area.

More than 90 per cent of the households in Valencia had regained power on Friday, utility Iberdrola said, though thousands still lacked electricity in cut-off areas that rescuers struggled to reach.

Officials said the death toll is likely to keep rising. It is already Spain's worst flood-related disaster in more than five decades and the deadliest to hit Europe since the 1970s.

WATCH | 'We need much more help,' says a woman in Paiporta:

'We need much more help': Spanish town tries to dig out after deadly floods

People filled the streets of the village of Paiporta on Friday to try to clear the mud and debris left behind by powerful, deadly floods in the Valencia region of Spain.

Marc Brimble, who lives in Catarroja, said people in the hard-hit town say this is the worst flooding they've ever seen.

In an interview on Wednesday with Nil Köksal, host of CBC's As It Happens, he said the flash flooding followed about a year of drought in much of the country.

"The rivers were so dry and so full of debris and bits of trees and dried plants that when the rains came, it just washed over everything," he said, adding that people in Catarroja were struggling to find drinking water because stores on the ground level were destroyed.

The extreme weather event came after Spain battled with prolonged droughts in 2022 and 2023. Experts say that drought and flood cycles are increasing with climate change.

In Chiva and other parts of Valencia — Paiporta, Masanasa, Barrio de la Torre, Alfafar — vast amounts of mud flowed into houses and crawled into cars, smashing some vehicles apart and easily lifting and moving others.

The storm this week unleashed more rain on Chiva in eight hours than the town had experienced in the preceding 20 months. The deluge powered a flood that knocked down two of the four bridges in the town, and made a third unsafe to cross.

Rivers of water also wiped out thousands of hectares of lemon and orange orchards, the main products of export for Spain.

The waters have now receded and the Civil Guard divers are gone, but police keep searching the gorge, smashed homes and underground garages, concerned that the mud could be hiding more bodies.

"Entire houses have disappeared. We don't know if there were people inside or not," Mayor Amparo Fort told RNE radio.

The storms concentrated over the Magro and Turia river basins and, in the Poyo riverbed, produced walls of water that overflowed riverbanks, catching people unaware as they went on with their daily lives, with many coming home from work on Tuesday evening.

The Valencia regional government has been criticized for not sending out flood warnings to mobile phones until 8 p.m. on Tuesday, when the flooding had already started in some places and well after the national weather agency issued a red alert indicating heavy rains.