"A tornado skipped across the county," Nashville Mayor John Cooper told the Tennessean. "You do have people at the hospital and frankly there have been fatalities."
Authorities asked people to stay inside until daybreak, when a rising sun revealed destroyed walls and roofs, fallen power lines, gas leaks, and broken trees. Schools, courts, and transit lines are closed.
Some polling stations were also hit and had to be moved, just hours before Super Tuesday voting is set to begin.
One tornado reportedly stayed on the ground from downtown Nashville into Hermitage, around 10 miles east of the city. Roughly 40 buildings collapsed around the city, according to Metro Nashville police.
Power outages are affecting more than 44,000 customers as of 4:00 a.m., according to Nashville Electric, which tweeted that four of its substations had been damaged.
"It is heartbreaking. We have had loss of life all across the state," said Gov. Bill Lee.