Overall, 19 casualties have stemmed from the string of storms, and the death toll is expected to rise. Alabama Governor Robert Bentley has declared a state of emergency in all counties.
Phil Bryant, the governor of Mississippi, told CNN that the twisters caused "severe damage" around Louisville and Tupelo. Louisville's largest hospital, the Winston Medical Center, was among the buildings hit by the whirlwind.
State emergency management authorities have said they're dealing with "multiple events over a wide part of the state," and that they expect the severe weather to continued.
"This is not over. It's going to last on into the night," chief Robert Latham said Monday.
The National Weather Service issued a tornado emergency Monday night in Athens, encouraging residents to seek shelter.
"This is an extremely dangerous tornado. You could be killed if not underground or in a tornado shelter," the warning stated.
Southeastern Tennessee, Moore and northwest Franklin counties also issued emergency warnings.
The latest warning issued by the National Weather Service says a major severe outbreak is expected to continue in portions of the southern and eastern U.S. through Wednesday.
"Widespread severe storms are expected with damaging winds, very large hail, and a few intense tornadoes," reads the warning.