While the tornado swept through eight southern states, communities like Tuscaloosa - home town of Alabama Governor Robert Bentley - have been virtually wiped away. Alabama, the worst-hit state, saw the death toll rise to 210, with more than 1,700 injured.
Up to one million people have been left without power. The Birmingham News quoted local officials as saying that it could take several days to restore electricity.
US President Barack Obama and First Lady Michelle planned to travel to Alabama on Friday to witness the damage. Obama has declared the storms a "major disaster" and ordered federal aid towards state and local recovery efforts. Included in the bill are grants for temporary housing and home repairs, and loans to cover uninsured property damage.
A state of emergency has been declared from central Oklahoma to Georgia, and governers called on the National Guard to help with rescue and clean-up operations.