Feb. 17 (UPI) -- Search-and-rescue personnel were working through dangerous weather conditions Tuesday to reach a group of six stranded skiers and locate 10 others unaccounted for in Northern California's backcountry following an avalanche, authorities said.

Rescue ski teams from Boreal Mountain Ski Resort and Tahoe Donner's Alder Creek Adventure Center have departed to reach the six known survivors sheltering at the avalanche site, while 46 first responders search for the 10 people unaccounted for, the Nevada County Sheriff's Office said in a statement.

Videos posted to the Nevada County Sheriff's Office Facebook page show a handful of people, seemingly rescuers, bundled up and walking through heavy snow underfoot and through a snowstorm.

The avalanche occurred at about 11:30 a.m. PST Tuesday in Castle Peak, located in California's mountainous Nevada County near Lake Tahoe, affecting the four ski guides and 12 clients of a ski tour.

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