One of four members of CERN's ski club swept down the mountainside, a 49-year-old Frenchman, died in the Sion hospital on Monday, Valais cantonal police said.
CERN spokesman Arnaud Marsollier, speaking to news agency ATS before news of the man's death became known, said the scientific organization was shocked by the news of the snow slide.
He confirmed that members of CERN’s ski club were victims of the avalanche on the north slope of Pointes de Tsavolire, a 3,026-metre mountain.
The other person critically injured is a 33-year-old Swiss man who lives in the canton of Geneva.
The man who died was a senior staff member of CERN's engineering department, Marsollier informed The Local.
"I must say that all CERN people are deeply saddened by this tragic news," he said.
Valais cantonal police said the avalanche, triggered on Sunday around 11am, occurred as five members of the club were ski touring in the Becs de Bosson Alpine region.
Four of the skiers were buried by the slide but the fifth skier was able to dig out two of the victims.
Emergency rescue workers retrieved the other two skiers, who were buried in more than two and a half metres of snow, police said.
They were transported in critical condition by helicopters separately to hospitals in Lausanne and Sion for treatment of life-threatening injuries.
CERN, which conducts particle physics research on the Swiss-French border, employs 2,250 staff and attracts additional researchers, sub-contractors and visiting scientists from around the world.
Its ski club includes an Alpine ski touring section that organizes regular outings with instructors.
"The group (involved with the avalanche) was indeed accompanied by an instructor," Marsollier told The Local.
"Such activities are done in the frame of the FFS (Fédération française de ski), respecting all the rules for such an activity," he said.
The participants of this outing were "experienced, used to ski touring," Marsollier added.
"As far as I know, we never had such an accident in the past within the CERN ski club — the ski club was founded in 1963."
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According to the ski club’s web page, participants of outings are required to have a list of safety equipment, including an avalanche transceiver (DVA), snow shovel, snow “probe” and first aid kit.
“Never forget that mountains are a hazardous environment,” the website says.
“Whatever precaution we take, there is always a risk remaining.”
Avalanches have already claimed 30 lives so far in the 2014-2015 winter season, making it the most deadly year since 2009-2010.