Eight skiers have died and one is presumed dead following an avalanche in the Sierra Nevada mountain range in California on Feb. 17. Six members of the ski group were rescued.

The 15-member skiing party, four guides and eleven clients, were engulfed in a storm-triggered avalanche near the Castle Peak area of Truckee, California, about 10 miles north of Lake Tahoe, at about 11:30 a.m. Pacific time on Feb. 17.

The skiers were returning from a three-day backcountry excursion at Frog Lake huts near Castle Peak when they were struck by the avalanche, about the length of a football field.

Six of the skiers huddled in a makeshift shelter constructed with tarpaulin sheets. They communicated with rescuers by radio beacon and text messaging until they were found.

Here's what we know so far: