Tornadoes, heavy rainfall, thunderstorms and flooding have forced evacuations and roof top rescues in Texas.
Around 2,000 people have had to be evacuated.
The state governor said the situation just south of Austin was the worst he has ever seen after a wall of water pulled down trees and destroyed homes.
As least three people have died including a 14-year.old boy and his dog who were found in a storm drain in a suburb of Dallas.
Schools have been closed and curfews extended in some areas.
The severe weather is expected to continue throughout the week.