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.

Authorities say at least 32 people have died because of the floods, and add that numbers will continue to change in the coming hours.