Twenty two people have died after a tornado ripped through Tennessee demolishing homes and leaving tens of thousands of residents without power.
At least 40 collapsed structures were reported in Nashville with some residents reported missing.
The tornado touched down northwest of the city shortly before 12.40am.
Nashville Mayor John Cooper said the city was "devastated", and urged people to "lend a helping hand" to neighbours.
Neighbourhoods throughout the city have been plunged into darkness amid infrastructure damage to power lines and other utilities.
Mayor Cooper added: "We all worry about some people being left in some buildings that have been damaged and I know the first responders are working their way through that problem."
"It is an ongoing search and rescue right now," Tennessee Emergency Community Relations Officer Maggie Hannan said.
In Putnam County the number of deaths has risen to 14, while two deaths have been confirmed in Wilson County, two in Davidson County, and one person in Benton County.
Around 44,000 people have been left without power, Nashville Electric said.
Police warned the danger was far from over.
"There are gas lines that are leaking, power lines that are on the ground, and multiple emergency responders are responding to those who are injured,” a statement read.
Those left homeless were yesterday being house at a shelter in a farmer's market.
Many of the city's schools, courts and transport lines were all forced to close.
Donald Trump tweeted his support on Tuesday morning: "Prayers for all of those affected by the devastating tornadoes in Tennessee. We will continue to monitor the developments. The Federal Government is with you all of the way during this difficult time.”
The tornado was the third to tear through downtown Nashville.
Cookeville in Putnam County, around 80 miles east of Nashville was hit especially hard.
One resident in the Germantown area told WTVF how she woke up as part of her roof was being ripped off.
She said: "It just woke you out of your sleep," she said. "I'm lucky my side didn't get torn off. The other side is totally torn off.""When you're inside it's one thing, but to walk outside and see this, it's bad," the woman told the affiliate.
Gov. Bill Lee said: "As tragic as this is -- and our hearts are broken -- we are certain that we'll surround these folks and we'll do what is necessary."
Previous twisters had ripped through the city in 1933 and 1998, America’s National Weather Service said.
