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.

Eight-year-old girls at sleep-away camp, families crammed into recreational vehicles, local residents traveling to or from work. These are some of the victims.

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

An intense bout of monsoon rains set the disaster in motion Tuesday afternoon. Water rushed from the surrounding mountainside, overwhelming the Rio Ruidoso and taking with it a man and two

As a climate scientist who calls Texas home, I can tell you that the Hill Country of Texas is no stranger to flooding. Meteorologists often refer to it as “Flash Flood Alley” because of its steep terrain, shallow soils, and its history of sudden and intense rainfall.

Arnold Duke joins The Lead

Up to 18 inches of rain fell between Aug. 18 and Aug. 20, 2007, triggering flash floods that are still considered some of Minnesota's worst. It killed seven people and caused $179 million in damages, mostly in Winona, Fillmore and Houston counties.

The four friends are among the hundreds of victims. The bodies of three of them have been found. Their families have searched for their loved ones since Friday.