Arkansas ? Before a wall of water swept through a narrow gorge in the Ouachita Mountains, worried forecasters sent warnings four times in a single hour to advise of the potential for flash flooding.

But those warnings, issued in the middle of the night, never reached vacationing families in a remote campground in the floodwaters’ path. The camp had no ranger on-site, no cell phone service and no sirens, and deputies at the nearest sheriff’s departments were at least an hour’s drive away.

By the time authorities could have reached the campsites, the Little Missouri River would have already risen by 14 feet and started to cut off low-water crossings.

As searchers on Monday recovered the body of a 20th person killed in the raging torrent, attention shifted to preventing similar disasters in the future.