Search and rescue crews on Feb. 18 entered their second day of looking for a group of nine backcountry skiers lost in an avalanche in California's Sierra Nevada mountain range.

The skiers went missing on Feb. 17 after the avalanche swept through the Castle Peak area, northwest of Lake Tahoe, at about 11:30 a.m., according to the Nevada County Sheriff's Office. They were part of a group of 15 returning from a stay at remote huts just north of Donner Pass.

Six members of the group survived and were rescued after crews battled harsh weather conditions for hours to get to them that evening. Two were taken to hospitals with injuries, the sheriff's office said. Originally, 10 people were thought to be missing but authorities later updated the number to nine.

The avalanche came as a powerful winter storm battered the region with heavy snow and high winds, the strongest winter storm of the year for the Lake Tahoe area. Interstate 80 was closed over the Donner Pass and up to 30 inches of snow were reported, according to the Reno Gazette Journal, part of the USA TODAY Network.

"We are actively coordinating additional resources statewide to support avalanche search and rescue efforts to locate missing skiers near Castle Peak," the California Office of Emergency Services said.