A man looks over buildings destroyed by the storms. Photo / AP
Tornadoes ripped across Tennessee as families slept early Tuesday (US time), shredding more than 140 buildings and burying people in piles of rubble and wrecked basements.
At least 25 people were killed, many of them before they could even get out of bed, authorities said.
Sirens and cellphone alerts sounded, but the twisters that struck around 2am moved so quickly that many people in their path could not flee to safer areas.
"It hit so fast, a lot of folks didn't have time to take shelter," Putnam County Mayor Randy Porter said. "Many of these folks were sleeping."
One twister wrecked homes and businesses across a 16km stretch of downtown Nashville. 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 3.2km path of destruction in Putnam County, wiping some homes from their foundations and depositing the wreckage far away.
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, an airport and the state Capitol were closed. More than a dozen polling stations were also damaged, forcing Super Tuesday voters to wait in long lines at alternative sites.
The death toll climbed steadily as first responders gingerly pulled apart wreckage. Sheriff Eddie Farris said only 30 per cent of the Putnam County disaster area had received a "hard check" by midday.
"A lot of these homes had basements, and we're hopeful there are still people down in there."
Nashville residents walked around in dismay on streets and sidewalks littered with debris, in neighbourhoods where missing walls and roofs left living rooms and kitchens exposed. Mangled power lines and broken trees came to rest on cars, streets and piles of rubble.
"It is heartbreaking. We have had loss of life all across the state," said Governor Bill Lee, who ordered nonessential state workers to stay home and then boarded a helicopter to survey the damage.
President Donald Trump announced plans to visit the disaster area on Friday.
"We send our love and our prayers of the nation to every family that was affected," he said.
"We will get there, and we will recover, and we will rebuild, and we will help them."
The tornadoes were spawned by a line of severe storms that stretched from Alabama into western Pennsylvania.
In Nashville, the twister's path was mostly north and east of the heart of downtown, sparing many of the city's biggest tourism draws — the honky tonks of Broadway, the Grand Ole Opry House, the storied Ryman Auditorium and the convention centre.
Instead the storm tore through the largely African American area of Bordeaux as well as neighbourhoods transformed by a recent building boom. Germantown and East Nashville are two of the city's trendiest hotspots, with restaurants, music venues, high-end apartment complexes and rising home prices threatening to drive out longtime residents.
"The dogs started barking before the sirens went off. They knew what was coming," said Paula Wade, of East Nashville. "Then we heard the roar ... Something made me just sit straight up in bed, and something came through the window right above my head. If I hadn't moved, I would've gotten a face full of glass."
Then she looked across the street and saw the damage at East End United Methodist Church.
"It's this beautiful Richardsonian Romanesque church. The bell tower is gone, the triptych window of Jesus the good shepherd that they just restored and put back up a few weeks ago is gone," she said.
The roof came crashing down on Ronald Baldwin and Harry Nahay in the bedroom of their one-story brick home in East Nashville.
"We couldn't get out," Baldwin said. "And so I just kept kicking and kicking until we finally made a hole."
The roaring wind woke Evan and Carlie Peters, also in East Nashville, but they had no time to reach the relative safety of an interior bathroom.
"Within about 10 seconds, the house started shaking," Carlie Peters said. "I jumped on top of the ground. He jumped on top of me. The ceiling landed on top of him. ... we're grateful to be alive."
With more than a dozen Super Tuesday polling places in Nashville's Davidson County damaged, voters were sent to other locations, some of them with long lines.
The Tennessee secretary of state delayed opening polls in the disaster area for an hour, but said they would close as scheduled Tuesday night. The Lawyers Committee for Civil Rights Under Law urged the governor and elections officials to extend the primary through at least the end of the week.
The tornado blew down a major Tennessee Valley Authority transmission line in Putnam County, and Nashville Electric tweeted that four of its substations were damaged, leaving more than 44,000 customers in the dark.
The severe weather also damaged gas lines, water mains and cellphone towers, making the rescue and recovery efforts much more difficult, authorities said.
Schools were closed in Nashville and beyond as families who were suddenly homeless tried to figure out their next steps. Hundreds of people went to a Red Cross shelter at the Nashville Farmers Market, just north of the state Capitol, but a power outage there forced them to move again to the Centennial Sportsplex.
The weather also reduced much of the interior of the long-closed Tennessee State Prison in Shelbyville to huge piles of bricks, the state Department of Corrections said in a tweet.
The prison formed the set of The Green Mile and other films.