An air ambulance and Coastguard helicopter were sent to the scene on the UK’s tallest mountain after police were alerted about 11:50am today.
Police have confirmed that two climbers injured following the avalanche had been taken off Ben Nevis, but one of them has since died.
The other has been airlifted to Queen Elizabeth Hospital.
Two others died at the scene and have been taken to Fort William.
Authorities said the avalanche had occurred in the number five gully area on the mountain.
Police are still trying to trace next of kin and have not yet named those involved.
Fort William Inspector Isla Campbell said: “This has been a challenging operation and I want to pass on my thanks to the mountain rescue teams, colleagues at the Maritime & Coastguard Agency and Scottish Ambulance Service for their assistance in extremely difficult conditions.
“I would also like to praise members of the public and staff from the Scottish Avalanche Information Service who were on scene at the time and provided immediate assistance.”
A Police Scotland spokeswoman earlier said: “We were made aware of an avalanche on Ben Nevis shortly after 11:50am this morning.
“Police Scotland is currently co-ordinating the mountain rescue response to this incident and is supporting partners at the scene.
“No further details are available at this time”.
The Scottish Ambulance Service were alerted to the incident shortly after 12:20pm.
Three ambulances were sent to the mountain’s peak.
A spokesman said: “We received a call at 12:22 hours today to attend an incident in Ben Nevis.
“We dispatched three ambulances, a Helimed resource and our trauma team to the scene.”
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.”
Ben Nevis, near Fort William in the western Highlands, is a popular destination for experienced climbers, attracting 125,000 visitors each year.
Today’s incident follows two recent fatal accidents on the mountain, which at 1,345m is the UK’s highest.
On New Year’s Day a 21-year-old German woman, who was a student at Bristol University, died after she fell from a ridge she had been climbing with three other people.
She had been hiking on what is known as the “ledge route” when she fell around 500ft.
Patrick Boothroyd, 21, from West Yorkshire, died in December after falling in the Tower Gully area.
Amber Boucher climbed Ben Nevis with friends on Friday and said they were “very lucky” to complete the climb in the conditions.
The group 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.
“There was an announcement over the weekend, I believe.
“We saw the risks yesterday. We still went and we were very lucky.”
After hearing the news on their way back to Wales, she said the group are “thanking our lucky stars”.