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.

President Donald Trump on Thursday expressed support for flood alarms in Texas and said he thinks “everyone’s doing a great job” responding to a disaster that has left more than 100 people dead and 170 people missing.

Over just two hours, the Guadalupe River at Comfort, Texas, rose from hip-height to three stories tall, sending water weighing as much as the Empire State building downstream roughly every minute it remained at its crest. The force of floodwater is often more powerful and surprising than people imagine.

New satellite imagery collected on July 8 shows the aftermath of the devastating flood along the Guadalupe River that swept through the area near Hunt and Kerrville, Texas. Loading... Throughout the area,