A man has died as Storm Desmond tore through Britain, bringing strong winds and heavy rain which caused Cumbria to declare a major incident.
The 90-year-old man, who died near Finchley Central station, north London, is believed to have been blown into the side of a moving bus by a gust of wind, a Scotland Yard spokesman said.
The Environment Agency declared 130 flood warnings, while residents in parts of Cumbria were evacuated from their homes.
The deluge left streets lined with terraced houses looking more like rivers as rescue teams set off in rubber dinghies to rescue stranded locals.
Bridges collapsed, rivers burst their banks and landslides were triggered as torrential rain swept through large swathes of the north of England and Scotland.
Prime Minister David Cameron said on Twitter: "My thoughts are with all affected by Storm Desmond. Teams are working to ensure swift response and help for those who need it."
Cumbria was the among the worst affected by the onslaught, and British Red Cross teams set up rest centres in Keswick, Appleby and Kendal, while medical groups issued an urgent call to draft in extra doctors amid fears the storm could cause casualties.
The village of Braithwaite was left "isolated" after the flooded river swept away the main bridge connecting it to the rest of the county.
Geoff Mawdsley, owner of the Coledale Inn, where many locals were seeking refuge for the night, described a "raging torrent going into the village" and said that a wall of the Coledale High Bridge had simply "gone".
Adrian Holme, from Cumbria Fire and Rescue Service, told the BBC the flood is "unprecedented" and "exceptionally challenging".
He said: "The events of today are absolutely devastating and unprecedented. The flood defences that were built here in 2012 haven't been breached, they have been over-topped. We have had 24 hours of constant rain."
He added: "This is absolutely devastating for the town of Keswick. As you can see behind us, the water is huge and there are hundreds of properties that have been devastated and flooded. And some of these people have been flooded three times, our hearts must go out to them."
It is believed that more than 100 people were evacuated from the town.
Flooding and landslides also brought disruption to Scotland, and homes were evacuated as rivers burst their banks in the Borders and Tayside.
And hundreds of homes in Wales were reportedly left without power as strong winds battered power lines.
David Hallows, emergency response manager for North Wales, said: "We would advise anyone whose area could be affected by Desmond to prepare a grab bag of essential items they can take with them if required to evacuate at short notice. This should include warm clothes, a torch and insurance documents."
A fire and rescue crew had to save a member of the public who was found clinging to a tree after they had tried to reach a horse stranded in a flooded field in Northumberland before being swept away by the flood water.
The RSPCA had to call off their attempts to rescue the creature because of the strength of the flood.