At least four people have died as a result of an avalanche in the French ski resort of Tignes, according to reports.
A group of skiers were buried after snow from the avalanche hit an off-piste area of the Alps resort.
Some reports say that as many as nine people, including a guide, were caught up in the incident and could still be trapped in the snow.
But local police have told the BBC five of the group may have not shown up for the session. Sky News said two skiers had been pulled out of the snow alive, but died shortly afterwards.
The 400-metre wide avalanche took place at an altitude of 2,100 metres, and struck during the busy half-term holidays period.
Authorities say all four of the skiers were French nationals.
The ski station said that the avalanche appeared to have been set off by a group of skiers higher up.
Rescue services deployed two helicopters and sniffer dogs to search for the missing skiers. Around 40 people are involved in the rescue operation.
The avalanche warning level at Tignes on Monday was three out of five at the time.
There have been 13 skiing accidents in the Alps and Pyrenees this winter, killing three people, making the Tignes incident the most serious of the season.
Last winter, there were 45 accidents, causing 21 deaths.