U.S. President Joe Biden has declared a major disaster exists in the state of Kentucky, where powerful tornadoes killed at least dozens of people, and he said that the catastrophic event was likely to be "one of the largest" storms in American history.

The declaration will pave the way for additional federal resources to be provided, after Kentucky Governor Andy Beshear made the request on Sunday.

Beshear said at least 80 people in the state were confirmed dead and the toll was eventually going to exceed 100. But later that day he revised the death toll to as low as 50 and said the original estimates could be wrong. 

The governor said he held out hope for "some miracles," even though it had been more than 24 hours since anyone was found alive in the rubble.

Casualties may be fewer than feared

Eight people were confirmed dead and eight were missing on Sunday at the Mayfield Consumer Products Candle Factory, where 110 employees were working on the night shift in the middle of the holiday rush when it was hit by tornadoes.

The candle company said on Sunday that while eight people remained missing, more than 90 others had been located.

Autumn Kirks, an employee at the candle factory, recalled the horrors of surviving the storm: "I pulled my safety goggles down, jumped under the closest thing, and seconds later I looked to my left and instead of wall there was sky and lightning and just destruction everywhere."

Kirks' boyfriend, who was also working at the factory, was among the victims. "I remember taking my eyes off of him for a second, and then he was gone," she told the Associated Press.

Layers of steel and cars 15 feet deep were on top of what used to be the factory roof, Beshear said. Rescue crews recovered pieces of peoples' lives – a backpack, a pair of shoes and a cellphone with 27 missed messages were among the items.

Watch: Kentucky candle factory worker goes live online for help

Entire communities 'gone'

Whole towns and over 1,000 homes are "just gone," said the governor, adding that going door to door in search of victims is out of the question in the hardest-hit areas because "there are no doors."

About 300 National Guard members went house to house, checking on people and helping to remove debris. Cadaver dogs searched for victims.

In Mayfield, a city of about 10,000 in western Kentucky, debris from destroyed buildings and shredded trees covered the ground. Twisted sheet metal, downed power lines and wrecked vehicles lined the streets. Windows were blown out and roofs torn off the buildings that were still standing.

Watch: Tornado cluster ravages swathes of Kentucky in U.S.

Authorities said they had little hope of finding survivors after the tornadoes tore through the U.S. Midwest and South on Friday night, killing at least 14 people in four other states and leaving tens of thousands without power.

Kentucky was the worst-hit state by far by the unusual mid-December swarm of twisters, which also killed at least six people in Illinois, where an Amazon distribution center was hit; two in Arkansas, where a nursing home was struck; four in Tennessee and two in Missouri.

(With input from agencies)