The monstrous, swift-moving flood that swept through the Hill Country of Texas killing at least 27 people and leaving many more missing, was a flash flood, the nation’s top storm-related killer

Meteorologists say incredible amounts of moisture in the air fueled a storm that barely moved over central Texas, creating conditions for fatal flash floods.

The death toll from sudden floods in the Texas Hill Country rose to 24 Friday night, officials said, as the search for more than 20 people missing from a girls summer camp continued through the night.