Searches are continuing in the US for survivors after a wave of tornadoes demolished properties in six states.
Scores of people have died and rescue workers and volunteers are helping residents sift through damaged homes to recover their belongings.
The emergency services have also been clearing fields of debris.
One of the worst hit towns was Mayfield in southwest Kentucky where many are without shelter.
At least 100 people are feared dead in Kentucky after a swarm of tornadoes tore a 320km path through the US midwest and south.
The powerful twisters, which weather forecasters say are unusual in cooler months, destroyed a candle factory and police stations in a small town in Kentucky, ripped through a nursing home in neighbouring Missouri, and killed at least six workers at an Amazon warehouse in Illinois.
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Kentucky Governor Andy Beshear said the collection of tornadoes was the most destructive in the state's history.
He said about 40 workers had been rescued at the candle factory in the city of Mayfield, which had about 110 people inside when it was reduced to a pile of rubble. It would be a "miracle" to find anyone else alive under the debris, Mr Beshear said.
"The devastation is unlike anything I have seen in my life and I have trouble putting it into words," Mr Beshear said at a press conference.
"It's very likely going to be over 100 people lost here in Kentucky."
He said 189 national guard personnel have been deployed to assist with the recovery.
Tornadoes: Devastating but still not well understood
The rescue efforts will focus in a large part of Mayfield, home to some 10,000 people in the southwestern corner of the state where it converges with Illinois, Missouri and Arkansas.
Video and photos posted on social media showed brick buildings in downtown Mayfield flattened, with parked cars nearly buried under debris.
The steeple on the historic Graves County courthouse was toppled and the nearby First United Methodist Church partially collapsed.
Mayfield Fire Chief Jeremy Creason, whose own station was destroyed, said the candle factory was diminished to a "pile of bent metal and steel and machinery" and that responders had to at times "crawl over casualties to get to live victims".
Paige Tingle said she drove four hours to the site in the hope of finding her 52-year-old mother, Jill Monroe, who was working at the factory and was last heard from at 9.30pm.
"We don't know how to feel, we are just trying to find her," she said. "It's a disaster here."
The genesis of the tornado outbreak was a series of overnight thunderstorms, including a super cell storm that formed in northeast Arkansas. That storm moved from Arkansas and Missouri and into Tennessee and Kentucky.
Unusually high temperatures and humidity created the environment for such an extreme weather event at this time of year, said Victor Gensini, a professor in geographic and atmospheric sciences at Northern Illinois University.
"This is an historic, if not generational event," he said.
Saying the disaster was likely to be one of the largest tornado outbreaks in US history, President Joe Biden yesterday approved an emergency declaration for Kentucky.
He told reporters he would be asking the Environmental Protection Agency to examine what role climate change may have played in fuelling the storms, and he raised questions about the tornado warning systems.
"What warning was there? And was it strong enough and was it heeded?" Mr Biden said.
'It's just totally gone, like a big bomb exploded'
About 209km east of Mayfield in Bowling Green, Kentucky, Justin Shepherd said his coffee shop was spared the worst of the storm, which struck other businesses hard on the busy commercial strip just off the bypass to US Highway 31 West.
"We've got some siding and roof damage here, but just across the road there's a brewery that half of it is gone. It's just totally gone, like a big bomb exploded or something."
One person was killed and five seriously injured when a tornado tore through a nursing home with 90 beds in Monette, Arkansas, a small community near the border with Missouri, according to Craighead County Judge Marvin Day.
"We were very blessed that more people weren't killed or injured in that. It could have been a whole lot worse," he said.
A few kilometres away in Leachville, Arkansas, a tornado destroyed a Dollar general store, killing one person, and laid waste to much of the city's downtown, said Lt Chuck Brown of the Mississippi County Sheriff's Office in Arkansas.
"It really sounded like a train roaring through town."
In Illinois, at least six workers were confirmed dead when an Amazon warehouse collapsed in the town of Edwardsville, when the winds ripped off the roof and reduced a wall longer than a football field to rubble.
Amazon truck driver Emily Epperson, 23, said she was anxiously waiting for information on the whereabouts of her workmate Austin McEwan yesterday afternoon to relay to his girlfriend and parents.
"We're so worried because we believe that, you know, he would have been found by now," she said.
Amazon chief Jeff Bezos said yesterday that he was "heartbroken" after at least six people were killed at the Amazon warehouse.
"The news from Edwardsville is tragic," Mr Bezos tweeted about the town where the facility was located.
"We're heartbroken over the loss of our teammates there, and our thoughts and prayers are with their families and loved ones."
(2/2) All of Edwardsville should know that the Amazon team is committed to supporting them and will be by their side through this crisis. We extend our fullest gratitude to all the incredible first responders who have worked so tirelessly at the site.
— Jeff Bezos (@JeffBezos) December 12, 2021
Severe weather claimed the lives of at least three people in Tennessee
In Tennessee, the severe weather killed at least three people, said Dean Flener, spokesperson for the state's Emergency Management Agency.
And two people, including a young child, were killed in their homes in Missouri, Governor Mike Parson said in a statement.
The National Weather Service's Storm Prediction Center said it received 36 reports of tornadoes touching down in Illinois, Kentucky, Tennessee, Missouri, Arkansas, and Mississippi.
Yesterday, Kentucky officials called on residents to stay off the roads and to donate blood, as responders rushed to rescue survivors and account for people in communities that had lost communications.
"We've got guardsmen who are out doing door knocks and checking up on folks because there's no other communication with some of these people," said Brigadier General Haldane Lamberton of the Kentucky National Guard.
