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.

Emergency officials are starting to focus on alert systems as they search for answers about how the flash flooding swept away so many.

Texas Gov. Greg Abbott says more than 160 people are believed to be still missing days after flash floods killed more than 100 people across central Texas.