Nine backcountry skiers are missing following an avalanche in California’s Lake Tahoe region on Tuesday, authorities say.

Six others have been rescued after they became stranded, the Nevada County Sheriff’s Office said.

The avalanche was reported about 11:30 PST (19:30 GMT) in the Castle Peak area near the town of Truckee, according to officials. Weather conditions remain dangerous, with a high chance of further avalanches.

“Highly skilled rescue ski teams” have deployed from two nearby ski resorts, the sheriff said. The six known survivors have been “directed to shelter in place as best they can in the conditions,” the sheriff added.

Officials initially reported that a group of 16 people in total – four guides and 12 clients – were involved, though that number was later lowered to 15.

“The six initially reported skiers who survived the avalanche have been successfully rescued this evening,” the sheriff’s office wrote on Facebook late on Tuesday night. Two of the six rescued skiers were taken to hospital, it said.

Experts from the nearby Boreal Mountain Ski Resort and the Alder Creek Adventure Center are also attempting to reach the site.

An earlier statement posted by the sheriff’s office said 46 emergency responders had joined the rescue efforts.

The Sierra Avalanche Center wrote in a forecast: “Large avalanches are expected to occur [on] Tuesday, Tuesday night, and into at least early Wednesday morning across backcountry terrain.”

The avalanche centre listed the danger rating as “high” – a four out of five on the rating scale.

“Travel in, near, or below avalanche terrain is not recommended today. A widespread natural avalanche cycle is expected over the next 24 hours,” the centre said. “Large avalanches may run through treed areas.”

The avalanche that trapped the skiers was rated as a D2.5 on a scale of D1 to D5, Sierra Avalanche Center Forecaster Steve Reynaud told local outlet ABC News 10. D2 avalanches can injure, bury or kill people, according to avalanche.org.

Reynaud told ABC that the skiers were on the last day of a three-day backcountry skiing trip.

He said the skiers spent two nights at huts on a trip that involved navigating “rugged mountainous terrain” for 4 miles (6.4km) while carrying food and supplies.

A spokesman for the sheriff’s office, Capt Russell Greene, told local news station KCRA-TV that it would be a “slow, tedious process” to find the missing skiers because of the high avalanche danger posing a risk to rescuers.

As of around 17:15 PST (01:15 GMT), he said first responders, including some on skis, were still trying to reach the avalanche zone and that those alive were sheltering under tarpaulin sheets “doing the best they can to survive”.

He said It was not uncommon for ski tour companies to take paying customers out in such conditions, adding: “I don’t think it was a wise choice but we don’t know all the details yet.”

California Governor Gavin Newsom’s office said in a post on X that state authorities were “co-ordinating an all-hands search-and-rescue effort” with local emergency teams.

The Boreal Mountain Ski Resort, which is near where the accident occurred, has reported 30 inches (76cm) of snowfall in the past 24 hours.

The resort decided to close on Tuesday because of high winds and low visibility.

The storm has also closed several highways, including Interstate 80 and Highway 50. (BBC)

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