As the Guadalupe River swelled from a wall of water heading downstream, sirens blared over the tiny river community of Comfort — a last-ditch warning to get out for those who had missed cellphone alerts and firefighters going street-to-street telling people to get out.

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."

At least 120 people have been found dead since heavy rainfall overwhelmed the river and flowed through homes and youth camps in the early morning hours of July 4. Ninety-six of those killed were in the hardest-hit county in central Texas, Kerr County, where the toll includes at least 36 children.

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.

President Donald Trump is visiting Texas on Friday to assess catastrophic flooding that has killed at least 120 people.

Follow for live updates in the Texas flooding as the death toll rises to 120, as rescue operations start to shift to recovery phase

The Houston Texans were the first to announce their donations on Saturday, July 5, with more coming throughout the week. The Dallas Cowboys and the NFL Foundation joined the Texans on Sunday, July 6, with each contributing $500,000 in a $1.5 million total donation.

A retired nurse, her son and a family friend say they were lucky to survive last week's flash floods in Texas that killed more than 100 people, including many summer campers.

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.

A retired nurse, her son, and a family friend say they were lucky to survive last week's flash floods in Texas that killed more than 100 people, including many summer campers.

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.

Over the last decade, an array of local and state agencies have missed opportunities to fund a flood warning system intended to avert the type of disaster that swept away dozens of youth campers and others in Kerr County,