Hours before a massive wall of floodwater barreled down a river in the heart of Texas Hill Country before sunrise on Friday, forecasters with the National Weather Service warned people that dangerous conditions were brewing.

Rescuers searched the Guadalupe River for survivors of the Texas floods that killed more than 100 people over the July Fourth holiday weekend, with an unknown number of people still missing. The basin area was crowded with families and campers preparing to enjoy the holiday when pounding rain brought about catastrophic flash floods just before dawn Friday.