The avalanche happened at about 5 p.m. Saturday, roughly eight miles west of Twin Lakes Village, the Lake County Office of Emergency Management said in a release.
Seven people were near the top of the ridge when the avalanche started; three were injured, two were unharmed in the incident, and two are still missing, the statement said.
Authorities said they would begin rescue operations at first light Sunday, CNN reported.
"We are seeing very dangerous avalanche conditions developing from basically the New Mexico border north to Wyoming," the Colorado Avalanche Information Center said in an advisory issued Saturday. "And the problem list is about as complicated as it can get. We are seeing very large avalanches taking out very old trees, mine buildings that have been around for many decades, and avalanches burying roadways with 20 feet of debris.
"People have been getting caught and killed in avalanches recently. These are glaring, flashing and obvious clues that things are not all good across our backcountry. We are seeing a snowpack that is teetering on the brink of critical mass."