This map shows where camps along the Guadalupe River were impacted by the July 4 flood. Meteorologists Pat Cavlin and Kim Castro detail how it all happened.

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 Texas Hill Country has been notorious for flash floods caused by the Guadalupe River. Here's why the area is called "Flash Flood Alley."

KERRVILLE, Texas (AP) — Over the last decade, an array of Texas state and local agencies missed opportunities to fund a flood warning system intended to avert a disaster like the one that killed dozens of young campers and scores of others in Kerr County on the Fourth of July.

Many Catholics in the region have been stepping up to help, converging on Notre Dame Parish in Kerrville, located in the hardest-hit community along the Guadalupe River.

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.

Along the Guadalupe River, a 60-room inn and nearby homes were quickly filling with water. Confusion, desperation and heroism ensued.

Follow along for developments on the July Fourth floods along the Guadalupe River in Kerr County and Central Texas.

A now-viral video posted by Larry Schaubhut Jr. on Friday, July 4, showed the river rising rapidly at the popular River Road property in New Braunfels, reaching 27 feet and sweeping away trees, furniture and gear. Schaubhut, who co-owns River Road Sky Cabins and River Road Treehouses, said he had just evacuated guests when the water surged.