A third hiker has died in the Grand Canyon in less than a month

A hiker died in the Grand Canyon on Sunday, marking the third death at the national park in the past month.

On Sunday, the Grand Canyon Regional Communications Center received a call about an unresponsive person on the Bright Angel Trail at about 2 p.m. Witnesses and first responders administered CPR on the person, but they were unable to resuscitate him.

The 50-year-old man was identified as being from San Angelo, Texas, according to the National Park Service. After staying overnight at the Havasupai Gardens campground, he began hiking toward the canyon’s rim.

A similar incident happened on June 29, when Scott Sims, 69, from Austin, was found semi-conscious on the River Trail. And on June 16, a 41-year-old man was found unconscious on Bright Angel Trail. Neither were able to be resuscitated.

In all three cases, no cause of death has been released yet, as authorities are still investigating.

The National Park Service has warned that temperatures on the trails can reach 120 degrees – in the shade. The agency advised visitors to avoid hiking in the inner canyon from 10 a.m. to 4 p.m.

Emergency responders may also take longer in the summer “due to limited staff, the number of rescue calls, employee safety requirements, and limited helicopter flying capability during periods of extreme heat or inclement weather,” the NPS said.