Bad weather in the Pigne d'Arolla area of the Swiss Alps on Sunday caught a group 14 skiers by surprise, police in the Valais canton said in a statement.
The manager of a mountain refuge in the remote mountain region sent out a call for help at dawn on Monday, triggering a major relief operation that involved seven helicopters, police said.
"Four people lost their lives, five others are in a critical state," the statement said.
Police indicated that one of those killed "likely" died from a fall and was found dead at the scene, while three others died later in hospital.
Some of those not described as being in critical condition are suffering from "mild hypothermia" but their "lives are not in danger," according to police.
The skiers were Italian, French and German nationals, police said, adding that efforts were under way to formally identify them and contact their families.
The group had set out from the Dix rest-stop and had intended to make it to the Cabanne de Vignettes refuge to sleep, trekking along a route called The Serpentine.
The fatal accident was the latest in a series affecting skiers in Switzerland in recent weeks.
German retail billionaire Karl-Erivan Haub went missing after skiing solo in the Swiss Alps earlier this month.
The body of the 58-year-old boss of Germany's sprawling Tengelmann retail group has not yet been found but authorities have given up hope of discovering him alive.
Mr Haub had reportedly set off from a lift at the Klein Matterhorn.
Separately, three Spanish ski tourers died after being engulfed by an avalanche that hit the Fiescheralp area of the Swiss Alps on March 31.
With AFP
