Hundreds of people were evacuated from their homes in northern England today as officials warned a dam could collapse following severe flooding that has killed three people.
Cyclists cycle through water on Cleveland Street in Hull, after heavy rain.
A man (68) and a teenager died in Sheffield and another man, in his 20s, was killed in Hull as torrential rain brought chaos to much of England and Wales.
Police and local authority officials said they had moved about 250 people from their homes near Rotherham in South Yorkshire after cracks appeared in the Ulley Dam.
The police commander for Rotherham, said it was difficult to tell whether the wall would collapse.
"It does have some cracks in it and there is just a steady flow of water at the moment which we're quite able to deal with in terms of the emergency response," he said.
Structural engineers are working to shore up the dam and pump out water from a reservoir covering more than 30 acres four miles south of the town.
"The water, if it escapes, will run into a valley area but would fairly rapidly spread out," Rotherham Council chief executive Mike Cuff said.
"It would reach the M1 motorway and it would then spread out. If the dam should burst, we would be talking in terms of maybe 15 minutes or so before water would reach residential areas."
The M1 was closed in South Yorkshire because of the flooding.
People in the Sheffield area were advised not to travel unless they had to. Police said the situation was exceptional, and council leaders said the unprecedented rainfall had caused millions of pounds of damage.
They also said there were around 1,400 people were being looked after in care centres after being evacuated from their flooded homes.
The Environment Agency has 25 severe flood warnings in place, with dozens of other rivers and canals on flood alert.
Yesterday a man died after in Hull after becoming trapped clearing a flooded drain. He had gone to help his grandfather but slipped and became pinned back by a torrent of water.
Elsewhere, police in South Yorkshire said Ryan Parry (14) had died after being swept away by the River Sheaf in Sheffield..