Three skiers who had flown by helicopter to a remote mountain range were swept away by an avalanche and likely killed under the weight of dozens of feet of snow, Alaska State Troopers said Wednesday.

While Alaska State Troopers had been unable to assess the ... witnesses saw the men deploy their avalanche air bags — inflatable vests meant to keep avalanche victims above or near the surface.

Poor weather prevented Alaska State ... vests meant to keep avalanche victims above or near the surface, Knutson said. The snow deposited by the avalanche was up to 100 feet (30 meters) deep ...

Alaska State Troopers said. After the slide caught the skiers, guides from the heli-skiing company that the group was with immediately tried to find the three missing skiers, according to troopers.

As the slide began, Knutson said, witnesses saw the men deploy their avalanche air bags — inflatable vests that are ... down a mountain, Alaska State Troopers said at the time.