Residents living south of the San Saba River in San Saba County have been ordered to evacuate due to river surging.

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."

On the night the deadly floodwaters raged down the Guadalupe River in Texas, the National Weather Service forecast office in Austin/San Antonio was missing a key member of its team: the warning coordination meteorologist,

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.

More than two dozen Mexican rescue volunteers and firefighters have been looking for victims and clearing debris along the Guadalupe River. Others were left waiting for visas and humanitarian permits to cross the border.

Multiple urban search and rescue teams from across the country that responded to the deadly floods in central Texas told CNN they were not deployed by the Federal Emergency Management Agency until at least Monday evening — days after any victim had been found alive.

The family had little time to think of a way out. They started using lobster buoys and a pocketknife to make a hole in the sleeping loft to escape.

Here's what to know about the deadly flooding, the colossal weather system that drove it and ongoing efforts to identify victims.

After hours of waiting and praying in the attic, the water stopped rising and the family was rescued. A first responder helped Matteson, wearing a navy and pink floral dress and quilted white jacket, into the back of a car. Her family survived. Their home was not so lucky.