A powerful flash flood tore through the Grand Canyon … leaving roughly 15 people unaccounted for and forcing dozens of others to evacuate.

The National Park Service says the major flooding struck Bright Angel Canyon and the Phantom Ranch area Saturday after a series of storms moved through the region.

As of Sunday, Park officials initially estimated as many as 20 people could be missing, but that number has since been revised to approximately 15 as authorities work to account for everyone who may have been in the area.

At least 62 people have been evacuated, with additional evacuations planned from Cottonwood Campground and Phantom Ranch. No injuries have been reported at this time.

One hiker, David Gregory, told CNN his group realized something was seriously wrong when the creek near their campsite suddenly turned dark with debris and began rushing rapidly. The group was ultimately rescued by helicopter and taken to safety.