Here’s what to know about the deadly flooding, the colossal weather system that drove it in, and around Kerr County, Texas, and ongoing efforts to identify victims.

At least 81 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.

Hurricane Katrina is the deadliest flood event in the U.S. in the past 25 years. The storm crashed into the Gulf Coast and caused devastating flooding when levees failed in New Orleans, where people had to be rescued by boat and helicopter from rooftops.