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.

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