Three people were feared dead after they were swept away in an avalanche while on a helicopter skiing trip outside Anchorage on Tuesday, officials in Alaska said.

The skiers were caught in a large avalanche around 3:30 p.m. local time near Girdwood, Alaska, a popular skiing destination about 40 miles southeast of downtown Anchorage, the Alaska Wildlife Troopers said in a statement.

The avalanche occurred in the west fork of the Twenty Mile River. The group was traveling with guides from a commercial heli-skiing operation, which escorts backcountry skiers.

Witnesses said that the three skiers deployed their avalanche air bags and “three guides on scene immediately issued a rescue alert,” according to Chugach Powder Guides, the helicopter skiing company that the skiers had hired. Four helicopters and eight additional guides went to the area to try to locate the skiers using avalanche beacons. But the guides determined that the three skiers were buried beneath 40 to 100 feet of snow and could not be reached, officials said.

— The New York Times