In what experts call "Flash Flood Alley," the terrain reacts quickly to rainfall steep slopes, rocky ground, and narrow riverbeds leave little time for warning.

Ten teenagers were killed after being swept away by rising floodwaters from the Guadalupe River while evacuating their summer camp in July 1987, according to the National Weather Service. (Credit: NWS

Two days before flash floods on the Guadalupe River in Texas killed dozens of campers at a Christian girls summer camp, a state inspector approved operations, noting there was a written plan for responding to natural disasters.

Texas inspectors approved Camp Mystic’s emergency plan just two days before devastating floods killed over 27 people, mostly children, at the Texas summer camp

The death toll from the July Fourth flash flood that ravaged a swath of central Texas Hill Country rose on Tuesday to at least 109, many of them children, as search teams pressed on through mounds of mud-encrusted debris looking for scores of people still missing.