Morpeth was inundated when the River Wansbeck burst its banks
Heavy rain that has affected parts of England and Wales may continue to cause flooding for several days, the Environment Agency has warned.
It said that while the rain has eased, river levels are still rising. Flash floods have hit Yorkshire, Shropshire, Herefordshire and Worcestershire.
Northumberland is particularly badly affected with an estimated 1,000 properties flooded in Morpeth.
Hundreds of people have had to spend the night in temporary accommodation.
Northumberland County Council member Andrew Tebbutt said Morpeth was "virtually cut off" from the outside world by the rising water.
BBC correspondent Chris Buckler said restoring houses in a clean-up operation would take months.
There were more than 80 flood warnings in place across England and Wales on Sunday morning. The north east of England is worst affected with seven severe flood warnings.
Five people have died in accidents related to the heavy rains.
Two people died in flash floods on Friday. A 27-year-old man died in a mudslide on a building site in Stroud, Gloucestershire.
Rescues, flooded roads and wrecked homes across the country
In Wales, a 17-year-old girl from Thamesmead, south London, died while on holiday in Powys when the 4X4 car she was travelling in overturned into a river.
A couple were killed when their car crashed into a tree in heavy rain in Plymouth, Devon, on Friday.
It has also emerged that a 42-year-old Sheffield man was killed when the Kawasaki motorbike he was riding hit a tree branch on the A66 on Friday afternoon.
Morpeth was inundated after the River Wansbeck burst its banks.
At least 110 people were rescued by boat in the area between 1600 BST and midnight and minibuses were also used to ferry people to higher ground. Many were elderly residents living in bungalows.
Police said hundreds of people sheltered on Saturday night at King Edward VI School after being evacuated from their homes, while a further 50 were at County Hall.
Mr Tebutt told the BBC about the rescue effort.
"It's frightful, it's awful, but we've been working hard and we've actually got some 400 people who we've evacuated," he said.
An RAF helicopter was called to help three stranded police officers on Saturday night.
A Northumbria Police spokesman said the officers had originally been called to help some motorists cut off by a landslide 10 miles west of Alnwick.
The members of the public were taken to safety, but the officers were trapped by another landslide at about 2100 BST. They were later led to safety unharmed at about 2330 BST by Northumberland Search and Rescue.
It's frightful, it's awful, but we've been working hard and we've actually got some 400 people who we've evacuated
The Environment Agency has warned of an increased threat of flooding as rainwater drains into river systems.
And it said the wet summer had not helped the situation, as it meant soils in many places were already saturated and unable to absorb any more rainwater.
The BBC Weathercentre said the picture would improve across north-east England on Sunday, with showers replacing persistent rain.
Between 5mm and 10mm of rainfall is expected on Sunday, compared with between 30mm and 40mm of rainfall on Saturday, a spokesman said.
The BBC's Wendy Urquhart said the Environment Agency is now turning its attention to coastal areas.
"With rivers flowing to the ocean and tides about to come in, there is a chance of flooding," she said.
The Scottish Environmental Protection Agency (SEPA) has six flood warnings in place, for Jed Water, Gala Water, Whiteadder Water, Blackadder Water and Langton Burn, Teviot Water and the River Tyne at Haddington.
In the Pickering area of North Yorkshire, several properties and roads have been flooded after the local beck burst its banks.
Firefighters rescue a man and woman trapped by floodwater
Fire crews have been on hand to pump out houses and residents have been told to move possessions upstairs.
In the village of Kirkley Mill, Northumberland, an RSPCA emergency team, called out to help some horses, found themselves rescuing a baby trapped in a car.
Many sporting and cultural events also had to be cancelled due to the wet weather.
Gloucestershire's biggest agricultural event, the Moreton-in-Marsh show, was abandoned, as were race meetings at Haydock Park, Merseyside; Stratford, Warwickshire; Gosforth Park, Newcastle, and Worcester, Worcestershire.
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