Flash flooding in Texas Hill Country has triggered one of the largest rescue operations in the state’s history.

Dozens of volunteers searched for bodies in Hunt, Texas, on July 6 after floods overcame the area days earlier.

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.