Grand Canyon, Arizona - About 15 people may be missing after a flash flood in Grand Canyon National Park, the National Park Service said in a statement Sunday.

There were no confirmed deaths or injuries, the park service said in an email.

Earlier, the park service said that more than 20 people were believed missing.

The flash flood, which began about 2:30 pm on Saturday, was caused by rainfall on the Kaibab Plateau, NPS said.

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The floods hit the Bright Angel Canyon and Phantom Ranch area on Saturday, the service said, adding that it was working with Arizona authorities to evacuate people and account for individuals in the affected area.

In a statement shared earlier on the National Park Service's website, the agency said it is looking for assistance in the matter.

"The National Park Service is asking the public to provide information for more than 20 individuals who may be missing or unaccounted for following a significant flash-flood event in Bright Angel Canyon and the Phantom Ranch area on August 29," the NPS said.

"The National Park Service is asking anyone who knows of hikers or backpackers who were in the inner canyon along the Bright Angel Creek corridor on August 29, as well as anyone who had a campground reservation in the affected corridor, to provide information to the National Park Service Investigative Services Branch (ISB).

"This includes individuals who may have been traveling along the North Kaibab Trail from the North Kaibab Trailhead to Phantom Ranch, staying at Bright Angel Campground, or traveling or staying in the area known as “the Box” north of Phantom Ranch."

The National Park Service said the Grand Canyon National Park staff, in coordination with the Arizona Department of Public Safety, continues to conduct evacuation and response efforts and is working to find individuals who may have been in the affected area. 

"If you know of anyone who may have been hiking or backpacking in these areas, please contact the NPS Investigative Services Branch Tip Line: 888-653-0009," the National Park Service said.