Search and rescue crews are continuing efforts near Castle Peak in Northern California’s Nevada County after an avalanche was reported late Tuesday morning. Six backcountry skiers survived but 10 remain unaccounted for, authorities said.

The Nevada County Sheriff’s Office said the avalanche was reported around 11:30 a.m. amid a heavy snowstorm that has closed both Interstate 80 and Highway 50 at the summit.

Six of the backcountry skiers “survived the avalanche” and were awaiting rescue at the site, the sheriff’s office said, while the other 10 remain unaccounted for. The group included four ski guides and 12 clients. 

Nevada County’s search and rescue team and other allied agencies are responding to the area to reach the six known survivors. Those other groups consist of highly skilled rescue ski teams from Boreal Mountain Ski Resort and Tahoe Donner’s Alder Creek Adventure Center, the sheriff’s office said. A SnoCat team was also launched from Alder Creek to assist.

California’s Office of Emergency Services said it is also coordinating to provide additional resources to assist with the search for the missing skiers.

An Avalanche Warning is in effect for the Central Sierra Nevada through 5 a.m. on Wednesday, according to the Sierra Avalanche Center. Avalanche danger was rated as “high” from below the treeline and above. 

Due to the extreme conditions in the Northern California high country, some ski resorts have suspended operations for the day — like Boreal Mountain, which is experiencing high wind and zero-visibility conditions. 

In January, a snowmobiler was caught in an avalanche near Johnson and Castle Peak and died. The snowmobiler was identified as 42-year-old Bend, Oregon, resident Chris Scott Thomason. 

This is a developing story.