Police in Valais canton said that search operations continued until 3:30 am (0230 GMT) on Saturday, then resumed after a break at 9:00 am.
Four dead in French Alps avalanche
Those still missing were identified as a Swiss citizen and two French nationals.
Vallon d'Arbi is a route best suited to skilled skiers, which is sporadically closed for safety reasons. Tourism sites recommend visitors ski with a guide.
Avalanche kills Swedish skier in Indian-held Kashmir
Police said the route was open at the time of Friday's avalanche.
The accident is the latest in a series of fatal incidents affecting skiers in Switzerland this season, with a series of avalanches killing three in the Swiss Alps last month.
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