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.

The Guadalupe River has a history of deadly flooding. Here is a look over the decades. (AP video Marshall Ritzel/Albee Zhang)

Flash floods surged through in the middle of the night, but many local officials appeared unaware of the unfolding catastrophe, initially leaving people near the river on their own.

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

At least 161 people remain missing in Kerr County, Texas, as authorities and volunteers search the Guadalupe River for victims.

In hard-hit Kerr County, the death toll has climbed to 95, including 36 children, Kerr County Sheriff Larry Leitha said at a news conference Wednesday.