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.

With more than 170 still missing, communities must reconcile how to pick up the pieces around a waterway that remains both a wellspring and a looming menace.

More than 100 people have been confirmed dead since July 4, when the Guadalupe River in central Texas swelled overnight and triggered flash floods that swept through an area known locally as “Flash Flood Alley.

When the precipitation intensified in the early morning hours Friday, many people failed to receive or respond to flood warnings at riverside campsites known to be in the floodplain.

Flash flooding is common enough around the crescent-shaped region from Dallas through the Hill Country, the area earned the nickname "Flash Flood Alley."

Also: San Antonio mourned the victims in a Travis Park vigil; UTSA said one of its teachers died in the Guadalupe River flood; Kerrville officials said a privately owned drone collided with a helicopter conducting search and rescue operations.

Hundreds of children at summer campsites along the Guadalupe River in Kerr County were at risk early Friday when a catastrophic flash flood killed at

Lt. Gov. Dan Patrick said rescuers are searching for survivors, including 23 girls missing from a Christian camp along the Guadalupe River.