A July Fourth weekend deluge in Texas caused catastrophic flash flooding that has killed more than 80 people. Camp Mystic in Kerr County says Monday morning that it is “grieving the loss” of 27 campers and counselors as the search continues for victims of the disaster.

At least 82 people are dead and at least 41 more are missing after devastating flash floods slammed Texas Hill Country, with water rescues taking place along the Guadalupe River, which rose rapidly early Friday morning to the height of a two-story building.

Search teams plodded through mud-laden riverbanks and flew aircraft over the flood-stricken landscape of central Texas for a fourth day on Monday, looking for dozens of people still missing from a disaster that has claimed at least 78 lives.