The National Weather Service issued a tornado emergency warning for the area around Athens, Alabama, near the Tennessee state line, on Monday evening, CNN said.
A tornado emergency also was declared in south-eastern Tennessee for east central Lincoln, Moore and northwest Franklin counties.
Storm spotters were tracking a large and extremely dangerous tornado seven miles east of Fayetteville, Tennessee, the weather service said.
The National Weather Service's Storm Prediction Centre declared tornado emergencies for several counties in northern Mississippi on Monday afternoon as the line of storms moved through the state from south-west to north-east.
Nearly 5 million people were at moderate risk of severe weather on late Monday, while 31 million people were at slight risk, including those in Atlanta and Nashville, CNN said.
The Arkansas tornado was the largest of several produced by a powerful storm system that rumbled through the central and southern US, according to CBSNews.
