NEVADA CITY, Calif. — Crews found the bodies of eight backcountry skiers and are searching for one more who was still missing on Wednesday after an avalanche in the mountains near Lake Tahoe, authorities said. The avalanche is the nation's deadliest since 1981.

Authorities have told the families the mission has moved from rescue to recovery, Nevada County Sheriff Shannan Moon said during a news conference.

Six others from the same group of skiers were rescued Tuesday. They were on a three-day trek in Northern California’s Sierra Nevada as a monster winter storm pummeled the West Coast.

While they waited to be rescued, the six survivors used equipment to shelter themselves and were trying to stay warm, Moon said. The survivors located three others who had died, Moon said.

Rescuers used a snowcat to get within 2 miles of the survivors, then skied in carefully so they didn’t set off another avalanche, the sheriff said.

The avalanche is the deadliest in the U.S. since 11 climbers were killed on Mount Rainier, Washington, 45 years ago.

Crews faced treacherous conditions during the search after the avalanche struck Tuesday morning. Search and rescue crews were dispatched to the Castle Peak area of the Sierra Nevada after a 911 call reporting the avalanche had buried 15 skiers.

One of those rescued after several hours of searching remained in a hospital Wednesday, Moon said. Heavy snow and the threat of additional avalanches slowed the rescue effort in the mountains near Castle Peak, northwest of Lake Tahoe.

The area near Donner Summit is one of the snowiest places in the Western Hemisphere and until just a few years ago was closed to the public. It sees an average of nearly 35 feet (10 meters) of snow a year, according to the Truckee Donner Land Trust, which owns a cluster of huts where the group was staying near Frog Lake.

The Sierra Avalanche Center warned Wednesday that the risk of avalanche remains high and advised against travel in the area. Multiple feet of snowfall and gale force winds in recent days left the snowpack unstable and unpredictable, and more snow was predicted to fall, the center said.

Nevada County Sheriff Capt. Russell Greene said authorities were notified about the avalanche by Blackbird Mountain Guides, which was leading the expedition, and the skiers’ emergency beacons. The sheriff’s office said Tuesday night that 15 backcountry skiers had been on the trip, not 16 as initially believed.

The skiers were on the last day of a backcountry skiing trip and had spent two nights in the huts, said Steve Reynaud, an avalanche forecaster with the Sierra Avalanche Center. He said the area requires navigating rugged mountainous terrain. All food and supplies need to be carried to the huts.

Reaching the huts in winter takes several hours and requires backcountry skills, avalanche training and safety equipment, the land trust says on its website.

Blackbird Mountain Guides said in a statement said the group, including four guides, was returning to the trailhead when the avalanche occurred.

“Our thoughts are with the missing individuals, their families, and first responders in the field,” Blackbird said in a statement Wednesday. The company said it is helping authorities in the search.

Several Tahoe ski resorts had been fully or partially closed due to the weather. Resorts, which use controlled explosions and barriers to manage avalanche threats, were not expected to be at as high of a risk as the backcountry, the center said.

The area near Donner Summit was closed for nearly a century before the land trust and its partners in 2020 acquired Frog Lake, which is framed by 1,000-foot-high (300-meter-high) cliffs. Donner Summit is named for the infamous Donner Party, a group of pioneers who resorted to cannibalism after getting trapped there in the winter of 1846-1847.

In January, an avalanche in the region buried a snowmobiler and killed him, authorities said. Each winter, 25 to 30 people die in avalanches in the U.S., according to the National Avalanche Center.