Officials in Grand Canyon National Park on Monday stressed the danger that extreme heat poses after a Texas man collapsed and died on a trail over the weekend.

The hiker, Scott Sims, 69, of Austin, was trying to reach Phantom Ranch for an overnight stay when he was found semiconscious at around 7 p.m. Saturday, the National Park Service said.

He then became unresponsive and a bystander began CPR, the park service said. Paramedics also responded, but they could not revive him.

Sims was found on the River Trail. He had been trying to get to Phantom Ranch using the South Kaibab Trail, the park service said. That trail can get up to 120 degrees in the shade in the summer, it said.

“Park rangers strongly advise not hiking in the inner canyon during the heat of the day between the hours of 10 a.m. and 4 p.m.,” it said.

Sims’ death is under investigation by the park staff and the Coconino County medical examiner, the park service said. A cause of death was not listed in a statement.

A park service review of deaths in national parks from 2014 to 2019 found that hiking was the second-deadliest recreational activity, behind driving.