Police in Switzerland say four people are dead after an avalanche hit a group of skiers in the southeast of the country.

Police in Graubuenden canton (state) say the avalanche on the slopes of the Piz Vilan mountain Saturday afternoon swept away seven members of a nine-strong group of skiers.

Rescuers recovered three bodies and four seriously injured people, who were flown to hospitals in St. Gallen, Zurich and Chur. Police say a fourth person later died at a hospital.

There was no immediate word on what triggered the avalanche.