The deluge of water caused flash flooding and landslides
The Foreign Office is investigating reports that a Briton is missing after flash floods hit the Portuguese island of Madeira, killing at least 40 people.
It is understood fewer than five Britons have been injured and are being treated in hospital.
The island's 2,000 UK tourists have been told they can venture out again after earlier advice to stay indoors, the travel association Abta said.
Eyewitnesses told the BBC the streets were littered with boulders and trees.
A spokesman at a hospital on the island said a British woman in her 50s was believed to be missing.
Peter Ramos, of Hospital Cruz de Carvalho, said out of the 120 patients seen on Saturday, three were from the UK.
A woman remained in hospital with multiple injuries, he said, while two men sustained minor injuries and had been discharged.
"Four people in a taxi were hit by floods," he added.
The Foreign Office said it was aware of reports that one British national was missing, and was "urgently investigating".
"We are providing consular assistance to a small number of British nationals who have been hospitalised," said a spokeswoman.
An Abta spokesman said: "The hotels have been largely unaffected, and the authorities have said people can leave their homes."
Some flights were cancelled and delayed on Saturday, but the spokesman said people due to travel out next week would be unaffected by events.
Rescue workers have begun searching streets and houses on the island after heavy rains on Saturday brought tonnes of mud and stones down the slopes of the island.
Streets were flooded in the regional capital city of Funchal - one of the worst-affected areas - and in other towns.
Water and power supplies, and telecommunications were also cut, although the weather improved on Sunday.
Mark Costa told the BBC on Sunday he was evacuated from his Funchal apartment because there was no electricity or running water and the underground car park was submerged.
The 30-year-old, from Bicester, Oxfordshire, was visiting his Portuguese parents who were celebrating their 40th wedding anniversary. All three were later relocated to a safer area of the city.
He said most of the water had now drained into the rivers but the roads around Funchal harbour were covered in mud.
"Looking out of the window, they have diverted the water back into the river," he said.
"People are walking about in the debris, just gasping at it."
He said Friday had been a "glorious" day but the rain had started on Saturday.
"We watched the river getting higher and higher. Some of the bridges have collapsed," he said.
"The noise of the boulders hitting each other was scary even from the fifth floor of the apartment."
Mark Gregory lives in Porto da Cruz, which is 30 minutes away from Funchal on the north-east coast.
"We experienced no more than heavy showers here. But when we ventured out this morning, as soon as we came out of the tunnel on the south side we were absolutely battered by the rain," he said.
"Drain covers were popping up and the roads were beginning to resemble rivers."
Former foreign secretary Margaret Beckett, who is staying on the Atlantic island, said the weather had been "really wild".
"One of the staff here said that in 46 years working in the same place he had never seen seas like it or winds like it, so it obviously has been quite exceptional," she said.
In the UK, families are struggling to contact their relatives in Madeira as many of the phone networks are down.
Martin Hellier, 38, from Yeovil, said he was trying to keep cool but growing increasingly concerned for his parents who live 20 miles (32km) west of Funchal in Ponta Do Sol.
He told the BBC he had heard no news in 24 hours because the phone lines were dead.
"My next course [of action] is to get in touch with the authorities over there and ask them what the conditions are in that particular region," he said.
"It's a tricky situation. I expect when the phone service is restored, they'll be in touch."
There has been widespread damage along the south coast of Madeira, with roads blocked, phone lines down and many people without water and electricity.
A Portuguese social services spokesman said communication problems were proving very difficult and warned the death toll would "likely increase, given the circumstances of this flood".
Portugal's Prime Minister Jose Socrates, who visited the island, said he was appalled by the destruction and promised all necessary help.