A t least 48 people are dead in central Texas in what officials called a "mass casualty event" after devastating flash floods slammed Hill Country, with water rescues taking place along the Guadalupe River.

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

The region is also known as “Flash Flood Alley,” because of its propensity for high levels of rainfall and the runoff on thin soil.