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.

Over 100 people have died after heavy rain pounded Kerr County, Texas, early Friday, leading to "catastrophic" flooding, the sheriff said.

President Donald Trump met with victims' families and surveyed the damage of catastrophic floods that struck the state one week ago.

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."

The organizations working together to help the flood victims said that 'no additional in-kind donations (clothing, food, supplies) are needed in Kerrville.' They said the best way to help is with monetary donations.

Plans to develop a flood monitoring system in the Texas county hit hardest by deadly floods were scheduled to begin only a few weeks later.

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.

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.

President Trump has not talked about eliminating FEMA as the emergency response agency helps with recovery efforts from the Texas floods.

"The first lady and I are here in Texas to express the love and support and the anguish of our entire nation in the aftermath of this really horrific and deadly flood," Trump said as he spoke at a roundtable event with first responders and local officials.