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.

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.

At Camp Mystic, a Christian summer camp in Hunt, Texas, where officials are grieving the loss of 27 children and counselors, belongings of the young campers were strewn about the flooded floors of a dormitory, while other items, including a pink backpack and a Camp Mystic T-shirt, were found along the bloated Guadalupe River, photos show.

Texas records show Camp Mystic had an emergency plan before floods killed at least 27 campers and counselors, but details of its storm response are still unclear.

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