emirates7 - More than 20 people may be missing or unaccounted for following a flash flood in Grand Canyon National Park in the US state of Arizona, authorities said Sunday.

The "significant flash-flood event" occurred in Bright Angel Canyon and the Phantom Ranch area on Saturday, the US National Park Service said in a news release.

Park officials said they are continuing evacuation and response efforts in coordination with the Arizona Department of Public Safety, while working to account for individuals who may have been in the affected area.

The flash flood caused significant damage to infrastructure throughout Bright Angel Canyon. Nearly all footbridges spanning Bright Angel Creek were destroyed, preventing hikers from crossing the creek, according to park officials.