At least 15 'missing or unaccounted for' in Grand Canyon after flash flood: Officials

Air evacuations continued at the Grand Canyon in Arizona on Sunday afternoon, a day after a "significant flash flood" swept through campgrounds and hiking trails at the bottom of the national park, authorities said.

The Grand Canyon National Park Service said in an update Sunday evening that there are at least 15 individuals "who may be missing or unaccounted" following Saturday's flash flood.

"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)," the statement said.

Earlier Sunday, the National Park Service (NPS) officials said more than 20 were missing and 62 individuals were air evacuated from Grand Canyon's Phantom Ranch and the lower North Kaibab Trail, "which was affected by a significant flash-flood event Saturday afternoon."

Evacuees were being taken to the Maswik Lodge Cafeteria on the South Rim of the Grand Canyon, where the American Red Cross is coordinating assistance.

No injuries were immediately reported.

"Multiple campgrounds and trails are closed until further notice, and there is no estimated reopening date for the affected areas," the Grand Canyon NPS said.

Grand Canyon National Park staff, in coordination with the Arizona Department of Public Safety, were continuing air evacuations on Sunday afternoon, officials said.

"Grand Canyon will possibly face additional thunderstorms and heavy rainfall today and Monday, which could result in flash flooding, debris flow, and rockfall," the Grand Canyon NPS statement said.

Flash flooding unfolded about 2:30 p.m. local time on Saturday in the Bright Angel Canyon and Phantom Ranch area, both popular destinations for hikers.

"The flash flood resulted in significant impacts to infrastructure throughout Bright Angel Canyon. Nearly all footbridges spanning Bright Angel Creek were destroyed, eliminating hiker access across the creek," the Grand Canyon NPS said.

Videos of the flooding obtained by ABC News show a roaring Colorado River as mudflows and debris from metal structures are seen floating down the river.

Erica Viola, who recorded the videos, told ABC News she was camping at Bright Angel Campground when she and her husband, Scott Svedin, had to evacuate. Viola said that she lost most of her belongings in the flooding.

Viola said that she and other campers were told by park rangers to run as fast as they could to the nearest bridge for evacuation.

Svedin said that as they were headed for the bridge, people were scrambling to beat the rising water.

"We just heard people yell, 'Run, run, run!' And there's 40 of us running through this deep, muddy water, trying to make it to the bridge," Viola said. "Once we got to the bridge, that's when this 15-foot wall of water came through the campground in Phantom Ranch and just wiped out all the bridges in the creek."

Viola and Svedin said they witnessed bunkhouses, barbecue grills, ice chests, and even an excavator floating down the Colorado River.

ABC News' Jennifer Watts and Lissette Rodriguez contributed to this report.