A fifth person has died from injuries sustained when an unexpected snowstorm surprised a group of 14 skiers in the Swiss Alps, forcing them to spend the night outdoors.

The group had set out from the Dix rest-stop and were heading to Vignettes to sleep, trekking along a route called the Serpentine. But bad weather in the Pigne d’Arolla area struck unexpectedly.

The manager of a rest-stop in the remote mountain region called for help on Monday morning, triggering a rescue operation that involved seven helicopters.

One person was found dead at the scene, and was believed to have died in a fall. Three others died soon after they reached hospital, followed by a fifth death late on Monday, police in Valais canton said. That person was likely to be among the five initially listed in critical condition. Others in the group were said to have mild hypothermia.

The victims were Italian, French and German nationals, police said, adding that efforts were under way to formally identify them. The families of the skiers had been informed.

In a separate incident, police said the bodies of two climbers, aged 21 and 22, were found on Monday, further east in the Alps in Bern canton. An alert was sounded late on Sunday but bad weather hampered rescue efforts.