GRAND CANYON, Ariz. (KPHO/Gray News) — Authorities said three people have died in heat-related incidents over the past week on Grand Canyon trails. Grand Canyon National Park rangers and first responders said two of the emergency calls came from the Inner Canyon trails, where temperatures in the shade can top 109 degrees in the afternoon. On June 12, a 72-year-old man was found not moving on the South Kaibab Trail.