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

A massive Texas search and cleanup effort was set to enter its fifth day Tuesday in response to Guadalupe River flooding that surged through the area on July 4.

The death toll from catastrophic flooding in Texas over the July Fourth weekend has surpassed 100 as the massive search continues for missing people.

As the search in Texas continued Wednesday for more than 160 people believed to be missing days after a destructive wall of water killed over 100 people, the full extent of the catastrophe had yet