Emergency helicopters and police and mountain rescue teams were scrambled to the scene in the French Alps.
Authorities are now searching for survivors from a skiing party of nine that was swept away by the avalanche, which struck an off-piste slope around 2,100m above Lake Tignes on the Lavachet slope.
Rescue teams have pulled out a victim from beneath the snow, and they are described as being in a critical condition.
The avalanche struck on an off-piste slope
Rescue helicopters stationed in Courchevel and Modane were called to the scene at around 11am.
Two people were pulled out alive, while three remain unaccounted for, rescuers said.
A search is now underway to find the missing skiiers who are thought to be trapped under the snow. The death toll is expected to rise.
The skiers were said to be on holiday in the resort and accompanied by a professional.
One official said: “An avalanche of 400 metres-wide was triggered on the off-piste sector of Tovière.”
Officials have warned it could take some time to find the buried skiiers.
Rescue helicopters were scrambled to the scene at 11am
In a statement the CRS said: "Today at 10.35am a 400-meter-wide avalanche broke out in the off-piste sector of Tovière.
"The alert was given by station personnel who saw the pouring and immediately warned the rescue workers.
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"The rescue teams were instantly mobilised thanks to the Tignes rescue trackers and several dog teams.
— Mathieu Cavada (@MathieuCavada) February 13, 2017
"Staff and ski instructors are currently lending a hand. The search is still ongoing. "
The tragedy has taken place during a particularly busy time for French skiing destinations, with families flocking to the resorts during the school half-term holidays
The Alpine ski resort, which is situated near the Italian border, is a popular destination for British holidaymakers.
The nationalities and identities of the victims are not yet known.
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