ARIZONA — A Texas man who was hiking at the Grand Canyon this week was found dead, park officials say.

The 67-year-old from Alvarado, Texas, was found unresponsive on July 8 at approximately 11:50 a.m. on the South Kaibab Trail. Bystanders initiated CPR until National Park Service (NPS) personnel and volunteers arrived.

“All attempts to resuscitate the individual were unsuccessful,” NPS officials said in a press release.

The man, who NPS has not named, was attempting to reach the Colorado River to stay at Phantom Ranch overnight. Officials say he turned around at Skeleton Point and was making his way back up the trail when the incident occurred.

The NPS is investigating the incident in coordination with the Coconino County Medical Examiner.

During the summer, temperatures on exposed parts of the trail can reach up to 120 degrees Fahrenheit. This, along with preexisting conditions and physical activity, can make hiking particularly dangerous and life-threatening, especially during peak heat hours of 10 a.m. to 4 p.m.

Officials encourage all visitors to take extreme caution when hiking during the summer months.