(NEW YORK) — A hiker who died at Grand Canyon National Park last week succumbed to suspected heat exposure, officials said.

The victim was identified as Catherine Houe, 49, of Daly City, California. According to park officials, Houe, her husband and a friend were planning to spend the night at Phantom Ranch, a lodge inside the Grand Canyon.

They had hiked about four miles down the South Kaibab Trail on Wednesday when Houe “became dizzy, disoriented, and then stopped breathing,” officials said.

The Grand Canyon Regional Communications Center received a call about the incident a little after 5:30 p.m. local time. CPR was performed and the National Park Service personnel responded via helicopter.

The cause of death is believed to be heat-related, park officials said. The high at Phantom Ranch that day was approximately 114 degrees, according to the officials.

The National Park Service said it is investigating the incident with the Coconino County Medical Examiner’s Office.

National Park Rangers are urging visitors to the Grand Canyon to be prepared for high temperatures in the coming weeks. Temperatures on the trails can reach over 120 degrees in the shade during the summer, officials said. Hiking in extreme heat can lead to heat exhaustion, heatstroke, hyponatremia and death.

This is the first death reported by the National Park Service this year in the Grand Canyon, which closed on April 1 due to concerns over the coronavirus pandemic. It started partially reopening to visitors on May 15.

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