The Utah Avalanche Center reports the first skier on the backcountry slope triggered a hard slab avalanche roughly to 2 feet deep and 200 feet wide.
The skier who triggered the slide was caught and carried through trees and sustained injuries.
The skiers told UAC they believe the skier was carried 500 feet down the hill before they came to a stop.
Ski patrollers from Park City Mountain responded to the out-of-bounds call and helped the party of three get out of the area.
The UAC reports heavy winds on Tuesday and Wednesday piled snow onto the north-facing slope, making for an unstable surface.
An avalanche was triggered in the same area Tuesday by a different group of skiers, but they were able to avoid getting caught in the slide.