Authorities claim that nine backcountry skiers are missing after an avalanche in the Lake Tahoe area in California on Tuesday.

The Nevada County Sheriff said six others had been rescued after they got stranded.

According to the officials, the avalanche happened at about 11:30 PST (19:30 GMT) in the Castle Peak region and close to the town of Truckee. The weather can be considered dangerous, and there is a significant possibility of additional avalanches.

“Two neighbouring ski resorts have sent our highly skilled rescue ski teams,” the sheriff said. “The six identified survivors have been instructed to shelter in the best way they can in the conditions,” the sheriff added.

Officials initially said there were a total of 16 individuals, including 4 guides and 12 clients, but this tally was later reduced to 15.

The sheriff office posted on Facebook late on Tuesday night that the “six initial skiers that survived the avalanche had been successfully rescued.” It said that “two out of six rescued skiers were hospitalised.”

The site is also being targeted by experts at the Boreal Mountain Ski Resort, situated nearby and the Alder Creek Adventure Centre.

A previous post by the office of the sheriff indicated that 46 emergency responders were part of the rescue mission.

According to a forecast that was posted by the Sierra Avalanche Centre, “it was expected that big avalanches would take place on Tuesday and Tuesday night and at least early Wednesday morning in backcountry terrain.”

The danger rating of the avalanche was rated to be high by the avalanche centre, four out of five on the rating scale.

It is not advised that anyone should travel in, near or below avalanche terrain today. The centre said, “a widespread natural avalanche cycle would take place in the next 24 hours. Large avalanches can be passed in the forested land.”

The avalanche that had struck the skiers was categorised as D2.5 out of the D1 to D5 scale, Sierra Avalanche Centre Forecaster Steve Reynaud informed the local outlet, ABC News 10. According to avalanche.org, D2 avalanches may injure, bury or kill people.

Reynaud told ABC that the skiers had been on a three-day backcountry skiing trip, which was ending.

On a journey that entailed going through rough mountainous terrain over a distance of 4 miles (6.4km), he said that the skiers spent two nights at huts and carried food and supplies.

Capt Russell Greene, a spokesman of the sheriff’s office, said through the local news channel, KCRA-TV, that it will be a slow, tedious process of searching for the missing skiers due to the high avalanche risks that are a threat to the rescuers.

At approximately 17:15 PST (01:15 GMT), he reported that first responders, including some using skis, were still attempting to access the avalanche area and that people still alive were under tarpaulin covers, doing the best they could to survive.

He replied that it was not unusual to go out in such conditions with paying customers in ski tour companies, and he said, “I do not think it was a smart decision, but we do not know all the details yet.”

In a post on X, the office of California Governor Gavin Newsom reported that authorities in the state were matching an all-hands search-and-rescue endeavour with local emergency crews.

Boreal Mountain Ski Resort, which is close to the accident site, recorded 30 inches (76cm) of snow in the last 24 hours.

The resort chose to close down on Tuesday due to bad winds and poor visibility.

Some highways are also shut down by the storm, such as Interstate 80 and Highway 50.