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.

Businesses large and small also sprang into action to help the community. Grocery chain H-E-B, which started in Kerrville, one of the cities affected by the floods, has been donating food and supplies through the Red Cross. San Antonio-based fast-food chain Whataburger said it would provide meals to first responders.