FRISCO, Colo. — A 71-year-old skier from Chicago’s north suburbs died after skiing in Colorado, authorities said.

William Hass, of Northbrook, was found unconscious on a Breckenridge run Monday afternoon, The Summit Daily reported. It does not appear that he crashed into anything while skiing, and Summit County Coroner Regan Wood said Hass died of natural causes.

Hass’ death was the fourth on the ski slopes in Summit County this season and the third that involved a medical problem. Along with the four deaths in Summit County, there have been at least three other skiing or snowboarding fatalities in Colorado this season.