According to a statement issued by the NPS on Saturday, the authorities received a report on July 14 saying two individuals were missing and multiple people injured after a flash flood struck a campsite on the Colorado River.
After rescue teams arrived at the scene amid active monsoonal weather, they sent five people to nearby hospitals in two days by helicopter, reports Xinhua news agency citing the statement as saying.
On July 15, one of those missing was found alive and unhurt, but the second, Rebecca Copeland, 29, from Ann Arbor, was dead, the park service said. They were found by people on a commercial river trip.
The NPS warned that flash floods are common in the desert southwest, including northern Arizona.
Arizona, where most part of the Grand Canyon National Park is located, has been receiving monsoonal rains this week, which caused flooding in parts of the state, including Flagstaff, a city close to the south gate of the park.
Arizona Governor Doug Ducey has issued a declaration of emergency in Coconino County, which includes Flagstaff.