SAN FRANCISCO (AP) — Six backcountry skiers were found alive and 10 others were still missing Tuesday after an avalanche in Northern California during a powerful winter storm moving through the state.

Search and rescue crews were dispatched to the Castle Peak area, northwest of Lake Tahoe, after someone called 911 to report an avalanche with people buried.

Ashley Quadros, a spokesperson with the Nevada County Sheriff’s Office, said the six skiers located were still awaiting rescue. Quadros said the survivors were asked to shelter in place “as best they can” while search and rescue ski teams reach them.

She said there are 46 emergency first responders trying to reach them.

The group included four ski guides with 12 clients, Quadros said.

The Nevada County Sheriff's Office received a 911 call at about 11:30 a.m. from someone reporting an avalanche with people buried, Quadros said.

The sheriff’s office, the sheriff’s Search & Rescue team and a crew with the California Department of Forestry and Fire Protection combed the area of Castle Peak, which is northwest of Lake Tahoe, Quadros said.

California is being walloped this week by a powerful winter storm carrying treacherous thunderstorms, high winds and heavy snow in mountain areas.

According to the Sierra Avalanche Center of the Tahoe National Forest based in Truckee, the area in the Central Sierra Nevada, including the Greater Lake Tahoe region, was facing high avalanche danger in the backcountry with large slides expected to occur Tuesday and into Wednesday.

The dangerous conditions were caused by rapidly accumulating snowfall piling on already fragile snowpack layers coupled with gale-force winds.

Source: WPLG