How rescuers raced against time to reach skiers trapped in avalanche

When authorities in Truckee, California, learned of a large avalanche that hit a group of backcountry skiers, they rushed into action.

Emergency messages came on Tuesday at 11:30 local time (19:30 GMT) from a group guide's iPhone, using satellite-texting capabilities, as well as from another skier's emergency distress beacon.

The 15-person group was at the end of a three-day trip to the Frog Lake Huts in the popular Castle Peak mountain region when the avalanche struck, according to the Nevada County Sheriff's Office.

But with nearby Highway 80 closed due to an ongoing massive storm, it was a challenge to reach the group, and authorities had to improvise.

The trapped skiers were directly across the snow-blocked highway from the Boreal Mountain Ski Resort, also closed due to the weather, but the resort was able to deploy rescue teams in an attempt to reach them. Another nearby resort, Tahoe Donner's Alder Creek Adventure Center, also sent teams. Some used a snow-cat, a manned vehicle that runs on treads in order to move on top of deep snow. They are most commonly used for grooming ski runs, but can also transport people.

By Tuesday afternoon, around 50 rescuers were working to reach the site, arriving from both the south and north of the mountain. At 17:30, they arrived at an area roughly two miles (3.2km) from where survivors were sheltering in make-shift tents, and had to ski in from there.

The accident site was about as large as a football field, according to officials.

For rescuers in any avalanche, time is crucial. People who are fully buried under avalanche snow normally die from asphyxiation in less than one hour. But, roughly half of avalanche fatalities in North America are caused by blunt force trauma, rather than burial, according to a recent study.

Rescue teams, as well as the group trapped by the avalanche, used special climbing skins on the underside of their skis, allowing users to travel uphill and through the backcountry.

Eventually, they found a group of six alive, stranded on the mountain and trying desperately to shelter from the storm.

Two of the six survivors had to be carried back and "could not walk because of the injuries they sustained during the avalanche," said Placer County Sheriff Wayne Woo. They were taken to hospital with non-life-threatening injuries. One person remained missing as of Wednesday afternoon, and is presumed dead.

Authorities on Wednesday said it was too dangerous to try to recover the bodies of those killed- seven women and two men - until the weather clears. Among the survivors, one was a guide and five were clients of the Blackbird Mountain guided tours. The entire group consisted of a mix of 11 recreational skiers and four ski guides.

One of the deceased was the spouse of a rescuer, but Woo said that even with the personal tragedy, the rescue team remains focused.

"Everybody has circled around to provide their love and condolences for this family," Woo said. "But I think it's also motivated the team of their purpose - to go out there and rescue those who were still alive, and now recover those decedents who are still out there."

Avalanche danger in the region remains high due to an unstable base and new snow that continues to "load" dangerous slopes, according to forecasters with the Sierra Avalanche Center.

They had warned on Monday of naturally occurring avalanches starting far overhead, and eventually coming down through the clouds.

While it is unclear exactly how rescuers found the survivors, skiers buried in an avalanche typically are advised to try to stick a hand out of the snow to alert rescuers, create a shell with their arms to ease breathing for as long as possible, and remove skis to avoid being pulled deeper into the snow. And experts warn against panicking, which can lead to breathing too quickly.

Backcountry skiers usually carry a shovel, beacon and probe as a precaution.

Each of the skiers in the California group had a beacon, probably the most vital tool in emergencies, to send out a signal to help pinpoint the user's location. Most ski trips begin with skiers' beacons in transmit mode but after an avalanche, survivors switch beacons to search mode, which use arrows on the device's screen and audio cues, to help rescuers find them.

Other safety devices are growing in popularity, including backpacks that inflate to help avalanche survivors, however officials in California say it's not known whether anyone in the group was equipped with these devices.

Authorities had initially been told that the group was made up of 16 people, but later said they found out that one person had backed out of the trip at the last minute.