Hundreds of motorists and rail passengers were left stranded overnight as extreme weather continued to wreak havoc across the UK - with forecasters warning the country “is not out of the woods yet”.
Strengthening winds caused blizzards and drifting snow in some parts, bringing roads to a standstill and leaving commuters facing travel disruption for the fourth day in a row.
Two police forces declared “major incidents” as the Army was drafted in to help rescue those left trapped in their cars.
Forecasters said the harsh conditions could last into next week, as yellow and amber weather warnings were put in place for virtually the whole of the UK.
The Met Office warned of more snow showers, power cuts, and potential damage to buildings as Storm Emma meets the blast of cold air from Siberia, known as the "Beast from the East".
Air and rail passengers faced the worst disruption since the cold snap arrived on Tuesday.
Up to 50,000 British travellers are believed to be stranded abroad following hundreds of flight cancellations. Heathrow is the worst hit, with more than 250 flights in and out of the UK's busiest airport cancelled on Friday, including long-haul flights to and from New York, Dubai and Singapore.
Bristol Airport was closed for most of Thursday and more than 60 flights on Friday have already been cancelled, while staff at Edinburgh airport were working overnight to clear the runway.
South Western Railway passengers were trapped in frosty carriages overnight after a broken-down train caused tailbacks on the rest of the tracks.
The train operator wrote on Twitter that a service had got into trouble near Christchurch, Dorset, requiring a "rescue train" to be sent to it.
Commuters reported being stranded in carriages with failing electricity and fluctuating temperatures.
Shane White was stuck on the 4.30pm service from Cardiff to Bournemouth until shortly before 8am on Friday morning.
He wrote on Twitter: "All sorts of problem all due to ice and snowy, apparently one train near Christchurch has welded itself to the track trying to move, obviously very high voltage going through these lines, but little current flow due to the ice build up.
"They have been trying all night to come up with a solution but trains have ran out of battery power etc, there was some rain that has frozen points and other electrical connections, with all the roads block and vehicle snowed in there is no road transport available."
Virgin Trains East Coast customers were told "NOT TO TRAVEL" by the train operator on Britain's flagship line, which connects Edinburgh, Newcastle and Leeds with London.
The message was echoed across the country, with Southeastern, the train operator for Kent and East Sussex, advising travellers to "postpone your journey".
Passengers on ScotRail and Arriva Trains Wales are likely to face another day of disarray over much of their networks. ScotRail warned: “Lines need to be tested in the morning to check if they are safe, which means there won’t be any services in the affected areas during the morning peak."
Rail travellers hoping to escape the country could also be affected, with Eurostar cancelling 10 trains linking London St Pancras with Paris and Brussels on Friday.
Hampshire Police said it had called in the military to help evacuate people from the A31, while Avon and Somerset Constabulary said about 100 vehicles had become stuck on the A303 at Ilminster.
In Greater Manchester, hundreds of drivers spent the night stuck on the M62, with police warning wind speeds had reached 90mph over the Rakewood Viaduct, between junctions 21 and 22.
Dave Webb, 37, from Wakefield, told the Press Association he had been on the motorway for 10 hours.
“We came to a halt at about 5.30pm last night and have been here since,” he said. “There hasn't been any snow since about 6.30pm but the wind is pretty strong and gusting.”
A group of volunteers in Milnrow, Rochdale, braved the conditions to take hot drinks, food and blankets to those left stranded, and opened up a community centre for those seeking refuge.
In the Midlands and the West Country, the military has been drafted to help hospitals cope in the treacherous conditions.
The Army sent 10 4x4 vehicles and 20 troops to Shropshire while the Royal Marines have deployed the same resources in Devon and Cornwall, after Devon and Cornwall NHS and Shropshire NHS asked for assistance.
An MoD spokesman said: "The MoD helps in cases of extreme weather when we receive a request from our civilian authority colleagues.
"There are three UK standby battalions held at high readiness to respond to UK contingencies and emergencies, including support to local authorities.
"We have the right people with the right training to respond to a range of contingencies."
Thousands of homes were without electricity in the north west of England on Friday morning as temperatures remained sub-zero.
Power company Electricity North West said power outages had affected parts of Stockport, Oldham, Preston, Blackburn, Bolton, Manchester, Carlisle and other parts of Cumbria and parts of Derbyshire, where 5,000 households are without power in Buxton alone.
The firm said that because of the high winds and heavy snow some of their work teams have had to stop repairs until it is safe to continue.
Yellow warnings for snow are in place for vast swathes of the country for the whole day, while a yellow warning for wind covers the North East of England and Wales until midday.
Temperatures will once again be below freezing for many parts of the UK during the day, with strong winds making it feel even chillier.
Met Office meteorologist Steven Keates said: “We are not out of the woods yet.
“There's further snow to come, as well as a wintry mix of sleet and freezing rain.
“Even parts of London and the South East are not immune to seeing more snow through the afternoon - not as much as yesterday, but still enough to cause further disruption.”
The whole of the Irish Republic is also on red alert, valid until 6pm on Friday, after being hit by the worst snow in 35 years.
Evelyn Cusack, senior forecaster with Met Eireann, warned 40cm of snow could fall in parts of the east and south.
In Scotland, troops were called in to transport medics to and from Edinburgh's two biggest hospital's after a request from NHS Lothian to the Scottish Government.
The extreme weather has seen health boards cancel non-essential operations and outpatient appointments on Friday, while NHS 24 has described its operations as being “stretched”.
Princess Royal Maternity Hospital in Glasgow also saw tiles fly from its roof under pressure from the extreme weather.
The so-called "Beast from the East" has already proved deadly. A seven-year-old girl became the latest to die during the severe weather on Thursday.
The child, believed to be a pedestrian, was fatally injured after a car hit a house on Bodrigan Road in Looe at about 2.30pm, Devon and Cornwall Police said.
A 75-year-old woman was earlier found dead in a snow-covered street in Leeds, while Hampshire Police said a 46-year-old man died after a collision involving a lorry and van on the A34 southbound near Tot Hill services.
A 60-year-old man who died after being pulled from the water at Danson Park, near Welling, south-east London, on Wednesday, was named by the Metropolitan Police as Stephen Cavanagh.
The National Grid also issued a “gas deficit warning” prompting fears of a shortage, but households were reassured domestic supplies would not be affected.
Nearly all train operators warned of cancellations and disruption again on Friday and hundreds more flights were cancelled.
Motorists across much of the UK have been warned against driving unless absolutely essential.
Additional reporting by PA
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