More than 2,000 people spent hours trapped inside the Channel Tunnel after five Eurostar trains broke down due to cold weather, BBC reported.
The trains failed as they left the cold air in northern France and entered the warmer tunnel.
Some passengers were evacuated via service tunnels to car trains, while others were kept on their trains. Many have faced gruelling 15-hour journeys.
Eurostar has cancelled all its services for Saturday.
Meanwhile, more snow and freezing temperatures are expected for parts of Scotland and south-east and eastern England.
Heavy snowfall caused travel chaos, forced schools to close and cut off power supplies in parts of the UK on Friday.
Although one Eurostar train is still stuck in the tunnel, there are no passengers on board.
John Keefe from Eurotunnel, the operator of the Channel Tunnel, said the situation was "absolutely extraordinary and unprecedented".
"There's never actually been an evacuation of a Eurostar train in the 15 years that the tunnel has been opened and last night we evacuated two whole trains to get people off."
Four trains have been moved from the tunnel but an empty one remains stuck.
The five trains were coming from Brussels and Paris, and Eurostar said the change in the atmospheric conditions caused a problem with their electrics.
Eurostar said some passengers were already back in England.
Director of communications Mary Walsh said the company was "extremely sorry" for the delays and refunds would be available for all those affected.
"We will also be looking at compensation," she added.
Many people are at terminals at either end of the tunnel, waiting to make the crossing or to be transferred to other stations in England.
Lee Godfree, a passenger evacuated from one of the stranded trains, said he and his family had arrived in Folkestone at 0500 GMT, having left Disneyland Paris at 1837 GMT.
He said their journey had been a "complete nightmare".
"We were without power. We ran out of water, we ran out of food and there was very, very poor communication from the staff," he told the BBC.
"We lost air conditioning when we lost the power. We had to open the emergency doors ourselves.
"The evacuation procedure we followed was one that we set down ourselves."
Mr Godfree, from Stowmarket in Suffolk, who was travelling with his wife and young son, was told there were 700 people on board their stranded train, where the "heat was unbearable".
He said there were pregnant women, people in wheelchairs and hundreds of parents with young children, and they got themselves on to the car train, where they sat on the "filthy floors".
The shuttle took them to Calais before heading back to England and they then had to wait for a train to take them on to London.
One of the stranded trains was towed out of the tunnel and taken directly to St Pancras.
Passengers from a second were evacuated from the stricken train by Eurotunnel shuttle and later transferred to a Eurostar train bound for St Pancras.
People on the third train were also evacuated to a service tunnel and then taken to the terminal in France.
The fourth and fifth trains were coupled together and hauled by a diesel train to England.
The problems with the Eurostar services had a knock-on effect for car passengers hoping to use the tunnel.
Eurotunnel assisted with the removal of the trains from the tunnel and at first the car service was suspended but it has since re-opened with "significant delays".
James Brownell and his friends had a 12-hour wait at Folkestone. They were due to catch the 1800 shuttle on Friday night but only arrived in France at 0500 GMT.
The 27-year-old from Essex said they were left in their car in "sub zero temperatures" but they luckily had duvets and blankets to keep them warm.
He said they were offered no food or water, and very little information.
"It was so frustrating, we did not have a clue what was going on," he said.
"There were babies in the car behind us. It has been a terrible 12 hours."
To add to passengers' difficulties, there is congestion around Folkestone and Dover due to the Channel Tunnel problems and the closure of the port of Calais due to severe weather.
Kent Police said bad weather in the county was also making driving hazardous.
Ch Supt Matthew Nix said: "Many people have spent a long time in their cars and other vehicles.
"We appreciate how difficult it is for them and our partners, supported by Kent Police, are making health checks and providing hot drinks and snacks."
It will take "considerable time" to clear the backlog of vehicles and people should only make essential journeys, he added.
The force has brought Operation Stack into effect - holding coast-bound heavy goods vehicles on the M20.
It means more than 2,300 lorries can be parked on the motorway.