Despite suffering internal bleeding and head trauma, the sole survivor of a rock climbing accident trekked for over 12 hours to find a pay phone to call for help.

Three people died and a fourth was injured while rock climbing in the North Cascades in Washington state, authorities said. Authorities in Okanogan County said the climbers were believed to be rappelling a steep gulley near North Early Winters Spire when their anchor failed,

Many details about what led up to the fall still aren’t known, said Cristina Woodworth, who leads the sheriff’s search and rescue team. But all four climbers appeared to be tied to the same piton when it failed.