A bridge collapsed as flash flooding hit part of North Yorkshire when a month's rain fell in four hours.
The region is braced for more rainfall as the Met Office has issued a yellow warning for rain across much of the north of England.
Some roads remain shut and rail passengers faced disruption after a landslip between Carlisle and Skipton.
The fire station in Leyburn flooded as crews were out answering emergencies.
The fire service had to pump out some new homes in the town after the water hit, some of the residents moved in just two months ago.
North Yorkshire Fire and Rescue Service said it received about 165 calls to flooding in Leyburn and Reeth on Tuesday evening.
A flood warning for Arkle Beck at Reeth and Low Fremington remains in place, according to the Environment Agency.
Swaledale Mountain Rescue Team posted a picture of a collapsed bridge in Grinton on Facebook, urging motorists to "only travel if essential as many routes impassable" due to flooding.
The damaged bridge, near Reeth, was on the route of the cycling World Championships held in Yorkshire on 29 September.
It also featured on the Tour de France route when the race visited the county in 2014.
Organisers of the world championships are due to visit the site to assess the damage .
Yorkshire 2019 Chief Executive Andy Hindley added: "We will address any damage to race routes with North Yorkshire County Council in due course."
Steve Clough, of the mountain rescue team, said: "The conditions were so bad that in the end only about 10 or 12 team members could make it there.
"The roads were a raging torrent and there were sheds and household oil tanks floating down them."
Mr Clough said his team spent more than eight hours searching properties in the area, rescuing about 10 people.
North Yorkshire Fire and Rescue Service helped many more and estimated "100 or more" homes had been affected, Mr Clough added.
"Some homes had a metre of water in them - it was horrific," he said.
Richard Attenburrow, whose neighbour's garage had fallen into his garden in Bellerby, said: "The whole wall came in and the roof and all its contents.
"That beck is normally three to four inches deep but last night it was eight or nine foot. It was ridiculous."
A holiday cottage business in Reeth has had to cancel future bookings after being flooded.
Guests in three of the cottages, owned by Rose Atkinson and David Atkinson, had to escape upstairs as the flow of the water downstairs was so strong.
Mr Atkinson asked on Facebook for help to pull furniture out of the cottages on Tuesday night.
His wife said: "We've had an army of volunteers who have come to help. The response from people in the village has been amazing. We are so thankful."
Some routes in the Yorkshire Dales remain shut but the fire service said there had been "no serious injuries".
Northern Rail said trains had been suspended between Ribblehead and Kirkby Stephen because of the landslip.
Anthony Ward filmed the flooded rail line from a train, shortly before the landslip happened.
The county was pounded by hailstones the size of "pickled onions" as a summer storm swept through and Malham Tarn in the Yorkshire Dales had 3.2in (82.2mm) of rain in 24 hours, the majority in the space of four hours.
The monthly average in the area for this time of year is 3.5in (89mm).
The fire service said: "If the road in front of you is flooded and you don't know the depth of the water don't risk driving through it."
The weather caused a mountain bike festival to be cancelled, as the organisers of the 2019 Ard Rock, near Reeth in Swaledale, said flash flooding had "submerged" the site, which was due to host the event from Friday.
Farmer Raymond Caldert told BBC Breakfast the flooding in Grinton was the worst he had ever seen and, if the festival had been running, lives could have been lost.
"I haven't seen anything like this," he said.
Mr Caldert added he had not lost any livestock but the flood washed away most of his 160 bales of silage.
Josie Beszant, who owns an art gallery in the town of Masham, said: "It was a very sudden and extremely heavy thunderstorm.
"Silver Street was flash flooded and fire engines came to pump it out. The gardens are pretty devastated. It just looks absolutely drenched."
'Disruption and long detours'
By Danny Savage, North of England correspondent
Travel conditions across the northern part of the Yorkshire Dales have been described by police as "shocking".
The main road along Swaledale linking Richmond and villages including Reeth and Keld has been washed away near Grinton.
Another road from Grinton over to Leyburn now has a gaping hole where for years there's been a bridge over a stream.
A violent hail and rain storm further west caused a landslide to block the main Settle to Carlisle railway line between Kirkby Stephen and Garsdale.
With it being peak tourist season in the Yorkshire Dales, the damage will cause disruption and potentially long detours for both visitors and residents living over a wide area.
Local farmer Andrew Loftus, said he had seen hailstones almost an inch (2.5cm) in diameter.
Gareth Walls, from Ripon, tweeted that they were "like pickled onions".
The Brymor Ice Cream parlour, near Masham, was caught in a freak hail storm that left some customers with minor injuries.
"Our parlour suffered damage to the roof, power failures and some visitors suffered minor injuries", it said on Facebook.
Leonie Garrard, who runs a clothing and interiors shop in Leyburn, said torrential rain caused water to come through the ceiling and left the town "cut off".
"I have never seen [anything like] this in my whole life. It has been horrendous."
An appeal has started to help those who have been hit by flooding. People have been urged to donate cash, food, clothing, bedding and other supplies to the Upper Dales Flood Relief Fund.
Councillor Stuart Parsons said the relief fund aimed to support victims who "have lost everything and while they are waiting for insurance to come through".
"Sadly, some of the people affected by the flooding might not have been insured," he added.