Nine skiers are still missing after a large avalanche swept the Castle Peak area of the Sierra Nevada mountains in California on Tuesday as authorities intensify desperate search and rescue efforts. 

The incident occurred around 11:30 a.m. on Tuesday near Lake Tahoe, where a group of 11 backcountry skiers and four guides had been spending three days when an avalanche engulfed them.

Officials immediately initiated search operations with rescuers trekking for hours in whiteout conditions before they were able to locate and rescue six members of the group, who had been stranded on Tuesday evening, with two of them eventually requiring hospitalisation.

“The six initially reported skiers who survived the avalanche have been successfully rescued this evening by search and rescue teams with varying injuries. Due to extreme weather conditions, it took several hours for rescue personnel to safely reach the skiers and transport them to safety, where they were medically evaluated by Truckee Fire.

“Two of the six skiers have been transported to a hospital for treatment. The search is ongoing, pending weather conditions. It should be noted that it was initially believed there were 16 total persons, but that number has been updated to reflect 15 people who actually went on the trip. No further updates are anticipated this evening,” the Nevada County Sheriff’s Office said in a statement on Tuesday night.

Meanwhile, the remaining nine members of the group are yet to be located, with authorities racing against time to rescue them. The sheriff’s office said 46 emergency first responders had joined the search party.

California Governor Gavin Newsom said that he “has been briefed on this developing incident. The state is coordinating an all-hands search and rescue effort with local partners and deploying resources to support the active response.”