Investigators are trying to determine what happened to a 49-year-old Lakewood woman who collapsed and later died while hiking in Black Canyon of the Gunnison National Park Monday afternoon.

The Montrose County Coroner’s Office says Tracey Lister had been on the Gunnison River trail when she collapsed.

Park rangers have since recovered her body from the park.

The coroner’s office is conducting an investigation and will release her cause of death.