A California agency that regulates workplace safety has opened an investigation into a skiing and rock climbing company following Tuesday’s Sierra Nevada avalanche that killed nine people, including three of the firm’s backcountry ski guides.

California’s Division of Occupational Safety and Health has until mid-August to investigate Truckee-based Blackbird Mountain Guides LLC, according to a spokesperson for the Department of Industrial Relations, Cal-OSHA’s parent agency.

“Under California law, the agency has up to six months to complete an investigation and issue citations if violations of workplace safety regulations are identified,” the spokesperson wrote in an email Wednesday evening to The Sacramento Bee. “The duration of an investigation may vary depending on the complexity of the circumstances.”

As with its other investigations, the agency will examine workplace safety and health practices involving the company’s California employees to determine whether the company violated state law.

Three of the people who were killed in the incident were working for the company as guides during the ski trip, Nevada County Sheriff Shannan Moon said during a news conference Wednesday. One of the guides was among those who were rescued.

Hampered by blistering whiteout conditions and the threat of another avalanche at the recovery site near Castle Peak, crews said Thursday they have been unable to remove the eight victims from the mountain. Another person in the skiing party remains missing.

Recovery efforts were expected to continue into the weekend, the Nevada County Sheriff’s Office said, and authorities said they would not release the victims’ names, ages, affiliations or hometowns until the mission was completed.

“Due to hazardous weather conditions, avalanche victims cannot be safely extracted off the mountain today,” the Sheriff’s Office said in a statement, adding that crews had worked “tirelessly around the clock” in dangerous conditions.

The group that was on the backcountry ski trip near Castle Peak had 15 people in all — four guides and 11 clients. Six people survived the avalanche. The victims included a mother of two who lived in the Marin County city of Mill Valley, according to the mayor there.

Zeb Blais, founder of Blackbird Mountain Guides, said in a statement late Wednesday that he was mourning the losses and that all guides in the group were trained or certified by the American Mountain Guides Association and also the American Institute for Avalanche Research and Education.

“We ask that people following this tragedy refrain from speculating,” the statement said. “We don’t have all the answers yet, and it may be some time before we do. In the meantime, please keep those impacted in your hearts.

Blackbird Mountain Guides is a Truckee-based company offering guided backcountry expedition vacations. It was founded in 2020 by Zeb Blais, according to California Secretary of State business records.

The firm also has offices in Bellingham, Washington, and Mount Shasta, according to its website. The company offers classes in avalanche safety, as well as skiing, alpine climbing and rock climbing.

The company offers trips around Lake Tahoe, Lassen Peak and Mammoth Lakes, as well as several areas of Washington state, according to the company. Internationally, it offers backcountry trips to France, Italy, Japan and South America.

Several similar companies are also based in the Sierra.

Cal-OSHA in December issued $221,000 in fines to a fireworks company after an explosion killed seven people in the rural Yolo County town of Esparto. In that instance, the division took about five months after the incident to investigate before issuing fines.

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