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Obwald cantonal police said the snow slide was reported to them shortly after 11am in the Laub area of the resort.
A 45-year-old Swedish citizen was flown in a helicopter by Rega emergency services to hospital for treatment of "moderate" injuries, police said.
Another Swede, 36, was treated for minor injuries while nine others were uninjured.
Ten of the eleven were able to dig themselves out of the snow unaided, while the other person needed help from fellow skiers, police said.
Seven of the skiers were part of a guided group.
The avalanche was described as being 300 metres wide and 800 metres long, occurring partway down the mountain on a slope identified as "off-piste" on the ski resort's map.
It occurred at a time when the WSL Institute for Snow and Avalanche Research had issued a warning for the region urging "caution and restraint."
Be careful out there folks. There's a huge amount of snow and more coming...