Flooding is the deadliest natural disaster facing Oklahomans, a threat far greater than tornadoes. In the United States, flooding kills an average of 103 people a year. Tornadoes, however, caused 48 deaths on average during the same period, according to the National Weather Service.

Key questions remain unanswered about the actions Texas officials took both before and during the catastrophic July Fourth holiday floods remain unanswered

Rescue efforts include more than 2,100 responders on the ground, private helicopters, drones, boats and cadaver-detecting dogs.