3 rock climbers fall to their deaths while descending steep gulley in Washington state; 4th climber survives

Three people fell to their deaths Sunday while rock climbing in Washington state, likely because of an equipment failure, authorities said. A fourth climber in their group survived the ordeal.

The climbers were descending a steep gully in the northern section of Early Winter Spire, a pair of rock formations in the Cascades some 150 miles east of Seattle, the Okanogan County Sheriff's Office said in a statement. 

What caused the deadly fall at the popular climbing spot is still under investigation, but the sheriff said it appears the climbers' anchors failed as they were rappelling down the rock face. Rappelling is a technique climbers use to hoist themselves down a vertical drop, with a rope and belay.