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.

At least 24 people are dead after heavy rain lashed Texas, leading to "catastrophic" flooding. Texas Gov. Greg Abbott said emergency responders remained in a search and rescue posture, hours after the flooding along the Guadalupe River inundated nearby areas.

The uncertainty about what happened at Mystic comes as local officials have repeatedly dodged questions about who was monitoring the weather and what measures were taken ahead of the flooding.