THREE climbers have died and a fourth was in hospital after they were swept away by a massive avalanche on the UK's highest mountain.

A wall of snow is said to have collapsed 4000ft down Ben Nevis leaving them no escape yesterday afternoon.

Two mountain rescue teams, an Army unit training nearby and two helicopters were diverted to the scene.

One man was found dead, another passed away despite frantic efforts to revive him at the scene. A third died a short time later.

The condition of the only survivor was still unknown in hospital.

Donald Paterson, deputy team leader of Lochaber Mountain Rescue Team, said: "They just got wiped out."

The tragedy occurred while the Scottish Avalanche Information Service issued warnings of a high risk of avalanches in the Ben Nevis area which stretches to 6pm today (Weds).

The warning said that “freezing” temperatures, heavy snowfall and strong winds linked to Storm Gareth will result in “high instability” on the mountain.

Just three days ago two people were carried down the mountain at 1pm after another avalanche in the same gully.

READ MORE: Female climber dies following fall on Ben Nevis

The Herald:

Inspector Isla Campbell of Police Scotland urged caution to those adventurers who were still considering tackling Britain's highest mountain.

"I would very much say to use to people, use all the resources that are available to you online... and very much think about the fact that you may have planned your trip and really want to come and enjoy the Scottish mountains, but nothing is worth risking your life for."

The four had endured freezing conditions at Number 5 Gully, which is seen as a winter climb at the easier end of the spectrum.

READ MORE: Climber dies after fall on Ben Nevis

But local climb experts say that it also has a reputation as a "notorious avalanche run" because of its broad upper section which attracts large accumulations of snow.

The alert to emergency services was made by a guide and an avalanche recorder from the SAIS who witnessed the avalanche which created a snow mound up to 2300 feet high.

One of the climbers was understood to have died instantaneously. Another died after desperate attempts to revive the person using CPR while another died while being taken down the mountain.

The fourth who was in a serious condition was stretchered halfway down the mountain to where a Helimed took him to hospital in Glasgow.

A fourth was airlifted to Queen Elizabeth Hospital in Glasgow for treatment.

A number of people in the area assisted to try and find anyone who had been caught up in the snow and quickly confirmed that four people had been caught by the avalanche.

A coastguard helicopter, the Lochaber and Glencoe Mountain Rescue Teams were alerted to take part in a massive rescue effort in very high winds, snowm, thunder and lightning.

Inspector Campbell indicated the high winds hampered the use of the helicopter.

The Herald:

Inspector Campbell said: "It has been very difficult conditions that the mountain rescue teams have faced today and the coastguard helicopter faced difficulties in that regard as well. "It has taken longer to get them off the hill than perhaps other days when the weather was more clement."

Mr Paterson added: "We did all we possibly good - we had every available person we could get hold of. There were four stretcher parties. We carried the bodies all the way down. It is a terrible tragedy.

"They were partially buried by it. We haven't had a lot of snow compared to normal but we have had fresh snow and high winds. This was a natural avalanche - it was not human triggered.

"The morning was nice but the conditions deteriorated as forecast. It was strong wings, snow, thunder and lightning - you name it. I was forced on to my knees four times just reaching the Charles Inglis Clark Memorial Hut on the mountain. It was brutal conditions."

First Minister Nicola Sturgeon said it was "absolutely tragic news".

She tweeted: "My thoughts are very much with the bereaved and injured. And my gratitude as always for the work of our emergency services, Mountain Rescue and Coastguard."

Skye, Lochaber and Badenoch MSP Kate Forbes said: "This is heart-breaking news. I'm sure that the hearts of everybody in the local area go out to those who are grieving. I sincerely hope that there are no further casualties."

"We have fantastic terrain in Lochaber that attracts thousands of climbers and walkers every year, and it is desperately sad when people come to harm."

A hiker who reached the summit of Ben Nevis said they were "very lucky" to complete the expedition.

Ambre Boucher and a group of friends set off from a local youth hostel, taking the mountain track to hike to and from the summit between 9am and 5pm.

"It was cold, heavy winds, snow flurries," the 41-year-old nurse from South Wales said.

"There was a whiteout at the top which got a bit scary, our footprints were being covered, but we managed to find our way down with another climber.

"We saw the risks yesterday. We still went and we were very lucky."

Ben Nevis, near Fort William, is a popular destination for experienced climbers, attracting 125,000 visitors each year.

According to the Scottish Avalanche Information Service, there have been four separate avalanches on Ben Nevis in the past month.

There have now been 11 deaths on Scotland's mountains this winter - but these latest three are the first due to avalanche. During the winter of 2012-13, eight people died because of avalanches.