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.

As early as July 2, officials at the Texas Division of Emergency Management, or TDEM, were publishing news releases warning that “heavy rainfall with the potential to cause flash flooding is anticipated across West Texas and the Hill Country” and were preparing resources such as swift-water rescue boat squads.