Six people were reported killed and 23 injured when tornadoes tore through parts of Tennessee on Saturday afternoon and night.
Chattanooga had also been under a tornado warning from 8:45 p.m. Saturday to 3 a.m. on Sunday.
The storm left nearly 50,000 people in the state without power as of Sunday morning.
Three of the deaths and many injured were at Clarksville.
Clarksville Mayor Joe Pitts declared a state of emergency.
Some houses in Clarksville were blown away.
Rescuers told of hearing cries for help from under debris.
There were also three deaths at Madison, a suburb of Nashville.
There was also significant tornado damage at Gallatin and Hendersonville, northeast of Nashville.