Aerial images of tornado-hit Tennessee have revealed the extent of the devastation caused by deadly twisters as the death toll stood at 24.
At least two twisters struck the state in the early hours of Tuesday, badly damaging more than 140 buildings and burying people in piles of rubble. Rescuers are still searching for people unaccounted for.
The tornadoes moved so quickly that many people in their path were still asleep and could not flee to safer areas.
They have caused widespread damage throughout Nashville, the state's biggest city.
State emergency officials, who initially reported at least 25 dead, have revised the toll to 24 fatalities after ruling one death counted earlier was not storm-related.
Around 150 people have suffered injuries and a number of people are still unaccounted for.
The scenes have been described to the BBC by locals as "like a war zone".
Resident David Haskell and his wife described sprinting to a storm shelter when emergency alarms went off on their phones.
"Ten seconds later the house just exploded," Mr Haskell told a Tennessee newspaper.
Putnam County Mayor Randy Porter said: "It hit so fast, a lot of folks didn't have time to take shelter.
"Many of these folks were sleeping."
The governor declared an emergency and sent the National Guard to the county to help with search-and-rescue efforts.
President Donald Trump has said he plans to visit the state on Friday.
Early findings by National Weather Service survey teams indicated that the damage in Nashville and Wilson County to the east was inflicted by a tornado of at least EF-3 intensity, the agency said. It is the third highest ranking for intensity, indicating severe damage to buildings and heavy cars lifted off the ground and thrown around.
One twister wrecked homes and businesses across a 10-mile stretch of Nashville that included parts of downtown.
It smashed more than three dozen buildings, including destroying the tower and stained glass of a historic church.
Another tornado damaged more than 100 structures along a two-mile path of destruction in Putnam County, wiping some homes from their foundations and depositing the wreckage far away.
Nineteen deaths have been recorded in Putnam County alone.
Daybreak revealed landscapes littered with blown-down walls and roofs, snapped power lines and huge broken trees, making many city streets and rural roads impassable.
Schools, courts, transit lines and an airport were closed. More than a dozen polling stations were also damaged, forcing Super Tuesday voters to wait in long lines at alternative sites.
A judge extended polling hours in Tennessee after the tornado hit as the US took part in the Democratic nomination race Super Tuesday.
