Flash floods in Texas have killed more than 100 people, many of them children. Heavy rains fell quickly in the predawn hours Friday in the Texas Hill Country.

The heavy rain that turned a river in Texas into a raging wall of water was fueled by unique atmospheric conditions, according to meteorologists and climate scientists.

Catastrophic flooding struck central Texas on Friday as the Guadalupe River surged by more than 20 to 26 feet within 90 minutes, causing widespread devastation and forcing mass evacuations in Texas Hill Country. At least 80 people have been killed in the floods while others remain missing or displaced and more than 850 people required rescuing.