Three people were killed and another person was injured in an avalanche that rumbled down a mountainside at Riffelberg by the Swiss Alpine ski resort of Zermatt, police said.

A spokesperson for police in the southern canton of Valais had no immediate details about the identities of the people caught up in the avalanche on Monday afternoon.

It was also unclear whether more people could still be missing, with police saying in a brief statement that search operations had been halted for Monday.

Access to the area, which had a lot of snow, was difficult, Valais police said.

The avalanche occurred just after 2pm local time, police said.

—AAP