Thousands of residents in the Derbyshire town of Whaley Bridge have been evacuated amid fears a dam could collapse after it was damaged by floodwaters.
Concrete panels on one side of the dam on the Toddbrook Resevoir, which holds back 300 million gallons of water, partially collapsed.
By 2.30pm on Thursday it was deemed too unsafe for people in the village below, who were ordered to "evacuate your property now".
There are concerns the village could be levelled if the dam, which dates to 1838, gives way.
Paul Nash and his partner Janet Williams barely had time to grab their cat and a few essentials before being forced to abandon their home.
They cannot know when – or if – they will see it again. "If the whole dam goes, it's going to cause absolute chaos," he said.
"Probably the village will go, because it [the river] goes straight through."
The couple joined an exodus of more than 6,000 people fleeing the centre of Whaley Bridge on Thursday as the concrete dam began to crumble.
The blotched notices hastily handed out by the emergency services left no room for doubt. "EVACUATE your property now", they read, "Take any medication and medical equipment with you."
As the heavens opened once more on Thursday night, the centre of the picturesque Peak District community was a ghost town, save for the sound of police going door to door, trying to coax out every last resident from the "red" danger zone.
Evacuees were told to gather at a school three miles away in Chapel-en-le-Frith while engineers began pumping water out of the reservoir to take pressure off the stricken dam.
It will take an estimated three days to reduce the volume to a safe level.
Experts are divided as to whether the concrete and earthwork structure will survive that long.
Dr Mohammad Heidarzadeh, an engineer at Brunel University London, said such designs could be "washed away very rapidly".
"Due to heavy rainfall in Whaley Bridge area, the spillway is now broken and a big chunk of its concrete structure is damaged," he said.
"There is a possibility that the spillway could then become fully broken in a few hours."
Anna Aspinall, 36, from Whaley Bridge, said she and others had been called to help place sandbags near the dam, but were sent away after structural engineers warned "that the wall is at high risk of failing".
She said: "We are praying the dam wall holds whilst the Canal and River Trust try to drain the water from the reservoir." The evacuation has been exacerbated by the deterioration of the roads in and around the town, following days of torrential rain.
Steve Cliffe, a pensioner, said the surface of the road to his hamlet of Fernilee, 1.5 miles away, was all torn up and the community completely cut off. "We just can't get out," he said.
Edwina Currie, the former MP, lives in a 400-year-old cottage above Whaley Bridge. "The first job is to lower the level as safely as possible – that means taking risks further downstream," she told the BBC.
"It's more important to try to save the dam and get it repaired."
As dusk fell last night the only vehicles in the main street of Whaley Bridge belonged to the emergency services.
A spokesman for Derbyshire Police said: "We understand that there will be some concern around not being able to return home. However, our priority is to ensure people are kept safe and well and are not taking unnecessary risks.
"This is not a decision that has been taken lightly and we appreciate there is a significant impact on this community. However, this is an unprecedented, fast-moving, emergency situation."
The Environment Agency has issued a severe flood warning, suggesting a danger to life, covering the River Goyt at Whaley Bridge. It states that the river could "rise rapidly" due to water rushing in from the reservoir.
"Horrified" residents fear the whole town could be "decimated" within minutes, witness says
Carolyn Whittle, 45, who lives in Meadowfield, on the hillside in Whaley Bridge, said she had never seen water flood over the dam in her lifetime.
She said: "We are situated north-west of the mouth of the reservoir, approx 400 feet about the water level.
"There is currently a request, we believe, for all to evacuate due to emergency services access.
"An hour ago, there was a lot of emergency service activity and frenzy while my son was trying to reach home. Another section of the concrete on the dam face has now collapsed.
"We have friend's children here with us, who would have had to camp out at the high school otherwise.
"Everyone I know is horrified that our whole town could be decimated in a matter of minutes, it's terrible.
"I've lived in Whaley for the best part of 45 years and I've never seen water flood over the dam like that, ever, nor thought that we could possibly be at risk in this way.
"We're gaining all our information from social at the moment. If we need to go, we will get in my defender and head over Disley tops. It's closed, but mainly to stop people trying to access Whaley centre, which police are not allowing at the bottom of our road.
"I'm really scared the dam will actually go. Best solution is a smaller flood of the Goyt river, with flood risks as far as Marple. When we went to see what was happening earlier, the fire brigade had arranged a tanker to pump water away from the reservoir, and a digger to dam the area where the river was still refilling the reservoir."