9 skiers missing after California avalanche

Rescuers are searching for survivors after an avalanche near Lake Tahoe, California, swept over a party of 15 backcountry skiers returning to the trailhead Tuesday. Six people have been rescued, with 9 still missing in the ice, rocks and debris.

The disaster at Castle Peak set off a dangerous, hours-long rescue effort that was hampered by extreme weather conditions that were hammering the skiers: Heavy snow and strong winds from the winter storm roaring through the rugged Sierra Nevada mountains in northern California. … "The search is ongoing, pending weather conditions," the Nevada County Sheriff's Office said late Tuesday.

Dozens of first responders arrived at the scene soon after the first call for help but conditions in the mountains are brutal. Continuing snowfall of 3 to 4 inches per hour fell Tuesday on terrain that's difficult even in good weather. The tour company, Blackbird Mountain Guides, advertises the Frog Lake Huts trip for those with intermediate-to-advanced skills: "The leadership team at Blackbird Mountain Guides is working in full coordination with the Nevada County Sheriff's Office and Nevada County Search and Rescue to support the ongoing rescue operation," the company said in a statement.

The stranded skiers were communicating with rescuers through emergency beacons – including some with the ability to send text messages, Captain Russell Greene of the Nevada County Sheriff's Office told CNN affiliate KCRA. The group crafted a makeshift shelter from a tarp, "doing everything they can to survive," Greene said.

Today will be critical for anyone still alive, as another storm arrives Thursday and is expected to bring even more snow.