RCMP said said a dozen people were injured in the slide on Boulder Mountain, near Revelstoke, B.C., but up to 200 people were on the mountain at the time for the annual Big Iron Shoot Out.
The slide struck around 3:30 p.m. local time, and search and rescue resources were called in from around the province and from Calgary.
Adam Burke, 20, a member of the Revelstoke Snowmobile Club, said his mother and many of his friends were up there at the time, but his mother was OK.
Burke said he chose not to go, because of the high-risk conditions in the mountains this weekend.
"Today it was high risk and just the other day it was extreme."
Every year someone dies on the mountains around Revelstoke and yet people continue to go there to ski or snowmobile. Seems to me those mountains should be closed by no later than the end of February and try to put a stop to this. Around about 200 people are missing.