A man died Saturday while hiking in the Grand Canyon National Park, according to the National Park Service .

Park authorities received a report at around 7 p.m. that Scott Sims, 69, of Austin, Texas, was semiconscious on the River Trail, the Park Service said. He was hiking to Phantom Ranch in Arizona, where he planned to stay overnight.

He became unresponsive shortly afterward and could not be resuscitated, despite attempts by bystanders and then Park Service paramedics.

A cause of death was not provided, but the Park Service noted in its news release that summer temperatures on exposed parts of the trail can reach over 120 degrees Fahrenheit in the shade. It advised hikers to avoid hiking in the inner canyon between 10 a.m. and 4 p.m., and noted that efforts to assist hikers could be delayed during summer months because of limited resources.

The Coconino County Medical Examiner and Park Service are investigating the incident.

Jessica Ryan, Sims niece, wrote on Facebook that she was with her uncle on the trek.

Greg, my uncle and I started a hike down to the bottom of the Grand Canyon via South Kaibab trail, she wrote. June 29, 2024 my uncle lost his life on the trail. There are no words for the events that transpired and the emotions we are feeling right now. Its not only what you see in movies. The most beautiful places are unforgiving. Be prepared. Dont underestimate nature. Hike smart.