US President Joe Biden has declared a national emergency after states were hit by more than 20 tornadoes on Friday, killing at least 83 people and wrecking entire towns.
The deadly tornadoes swept across seven central and southern US states – demolishing buildings and trapping people under rubble.
At least 83 people are dead and dozens more people are missing after entire towns were destroyed by the tornadoes.
Rescue workers are now carrying out a desperate search for survivors across the affected states.
Mr Biden has signed a Federal Emergency Disaster Declaration, releasing funds for Kentucky, the worst-hit state, as he told how the deadly weather was “largest tornado outbreaks in US history”.
The president, who has ordered federal aid to supplement the response from state and local authorities, said the government will do everything it possibly can to help central areas of the country devastated by tornadoes.
Mr Biden told reporters: “It’s a tragedy. And we still don’t know how many lives were lost and the full extent of the damage.”
The president also questioned tornado warning systems after the US National Weather Service issued its highest alert on Friday night for the states of Kentucky, Arkansas, Tennessee, Missouri and Illinois.
He said: “One of the questions that are going to be raised, I’m confident, is: What warning was there? And was it strong enough and was it heeded?”
Mr Biden 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.
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Andy Beshear, the Governor of Kentucky, said the collection of tornadoes was the most destructive in the state’s history.
The powerful twisters destroyed a candle factory and the fire and police stations in the small town of Mayfield, Kentucky.
National Guard personnel have been scrambled to assist with rescue efforts in large part on Mayfield, home to some 10,000 people.
They also ripped through a nursing home in neighbouring Missouri, and killed at least six workers at an Amazon warehouse in Illinois.
Mr Beshear told how about 40 workers had been rescued from a candle factory in the city of Mayfield, which had about 110 people inside when it was reduced to a pile of rubble.
He said at a press conference: “it would be a “miracle” to find anyone else alive under the debris
“The devastation is unlike anything I have seen in my life and I have trouble putting it into words,”
“It’s very likely going to be over 100 people lost here in Kentucky.”
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 9:30 p.m.
“We don’t know how to feel, we are just trying to find her,” she said. “It’s a disaster here.”