About 300 people were left trapped in their cars
About 300 people have been rescued from vehicles, including a school bus, after they became stuck in snow near Londonderry, police have said.
The rescue focused on 120 vehicles trapped on the Glenshane Pass.
It came as heavy snow and winds caused widespread problems across Northern Ireland with 48,000 homes left without power.
Northern Ireland Electricity said there were currently more than 600 individual faults across the network.
NIE said that widespread damage had been caused by the weather, especially in Omagh, Enniskillen, Dungannon, Downpatrick, Derry, Coleraine and Ballymena.
Problems were caused by snow and ice sticking to power lines which were then being blown over.
It said 70 additional engineers and linesmen were making their way to Northern Ireland on Wednesday from the rest of the UK and the Irish Republic to bolster the group of 450 NIE employees already mobilised.
The Roads Service said they were facing "unprecedented" conditions.
A number of schools and roads have been closed across Northern Ireland due to the weather.
Roy Coulter of NIE said that although 48,000 customers were currently without power that number would probably rise during the morning.
"We have about 450 engineers, linesmen, tree-cutters, call agents, admin staff and our colleagues in the Agency Supply Board are assisting us to restore supplies.
Cars abandoned at the Glenshane Pass
"Some of the people have worked through atrocious weather conditions right through the night in up to 300mm of snow.
"There was very poor visibility and wind so strong they couldn't actually climb poles."
The Met Office issued extreme weather warnings for Northern Ireland.
Forecasters predict heavy snowfall through the morning.
BBC weather forecaster Laura Tobin said that although snow was forecast to move away from Northern Ireland, freezing temperatures would make driving conditions treacherous.
Chief Inspector Steven Cargin, of the Police Service of Northern Ireland, said the Glenshane Pass rescue operation had involved police, mountain rescue and coastguard workers.
Motorists were taken to Dungiven Leisure Centre, in County Derry, only for a power failure to strike, forcing them to relocate to nearby Limavady and Gulladuff.
Police said no-one had been injured in the operation, although nine people had refused to leave their vehicles.
Jackie O'Hagan, who was one of those rescued, described the experience as being akin to "Armageddon".
"It was rough, it was not pleasant, but the efforts from the mountain rescue teams, the police and the people of Dungiven and Limavady have been second to none," she added.
A snowplough at work on the Derry-Belfast road at Claudy
Martin McMullan of one of the mountain rescue teams described the scene which greeted them on Tuesday night.
"As we arrived, although people were trying to clear the roads, the snow was continuing to fall and it was just making it much more difficult to get to people and to get them back out of the area," he said.
"Some people were quite able to walk with assistance to nearby vehicles, there were several people that actually had to be stretchered because the conditions were too extreme for them."
About 200 air travellers were left stranded at Belfast International Airport on Tuesday night after several flights were cancelled because of the weather.
Some passengers criticised the airlines for not giving out enough information before they were eventually bussed to hotels for an overnight stay.
Meanwhile on Wednesday, a spokesperson said the airport "has experienced several cancellations and delays this morning as a result of last night and this morning's adverse weather conditions".
"Whilst the airport is fully operational the knock-on effect is that we expect further delays this afternoon and passengers are strongly advised to check with their airline before travelling."
Police have said driving conditions across Northern Ireland are "treacherous" and advised motorists to slow down.
A number of roads are currently closed. These include the Glenshane Pass, the Legavallan Road from Dungiven to Garvagh, the Rathkeel Road outside Broughshane and the Glenariff Road at Cushendall.
The Shanes Hill Road between Ballymena and Larne is closed. Police advise motorists to avoid the Collin Road between Broughshane and Ballyclare.
Craigmore Road in Newry is closed between Dennison Yard and the Forkhill Roundabout as NIE deal with fallen electricity cables.
Police said they had received reports of fallen cables on the Frosses Road but further details about the location were not currently available.
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