There were at least 44 tornadoes reported across nine states between Friday night and early Saturday morning -- unusual for December in the United States. Kentucky was the worst-hit state, with at least 74 confirmed fatalities, according to Kentucky Gov. Andy Beshear, who cautioned that figure "is fluid" and "will change."
"Undoubtedly, there will be more," Beshear told reporters during a press conference Monday.
The governor, who has two relatives among the dead, fought back tears as he revealed the age range of the known victims. He said 18 bodies have yet to be identified.
"Of the ones that we know, the age range is 5 months to 86 years old and six are younger than 18," he said.
On average, there are 69 tornado-related fatalities in the U.S. each year, according to data from the National Oceanic and Atmospheric Administration. The deadliest twister on record to hit Kentucky occurred on March 27, 1890. There were 76 deaths.
Kentucky alone was hit by at least five tornadoes between Friday and Saturday, including one that stayed on the ground for some 200 miles, "devastating anything in its path," Beshear said.
At least 18 counties in Kentucky reported lives lost, and 18 counties reported damages. As of Monday morning, some 30,000 homes in the southeastern state were still without power, according to Beshear.
"Thousands of homes are damaged, if not entirely destroyed," he told reporters. "We're not going to let any of our folks go homeless."
Beshear acknowledged that it will take time to rebuild from what he described as the "worst tornado event" in Kentucky's history and doubted whether it would have been possible to be better prepared.
"I don't think anyone could have predicted something as devastating as this," he said. "I don't fault warning systems, I don't fault training."
He then posed the question: "How do you tell people that there's going to be one of the most powerful tornadoes in history and it's going to come directly through your building?"
At least 300 members of the Kentucky National Guard have been deployed across the state to help local authorities remove debris and search for survivors as well as victims, according to Beshear.
"There is significant debris removal going on right now, but there is just a mountain of waste. It is going to take a significant amount of time," he said. "We've got significant livestock dead in all of the areas -- there's ongoing cleanup with that, too."
In an interview with ABC News' David Muir on Sunday, the Kentucky governor said rescuers have pulled some survivors from the rubble.
"We are still hoping for miracles," Beshear added. "We are finding people and every single moment is incredible."
Speaking to reporters Monday afternoon, Beshear said more than 20 deaths were in Kentucky's Graves County, where Mayfield is the county seat. Another 17 deaths were reported in Hopkins County, 11 in Muhlenberg County, 15 in Warren County, four in Caldwell County, one in Marshall County, one in Taylor County, one in Fulton County, one in Lyon County and one in Franklin County, according to the governor.
Beshear said the latest confirmed death was a government contractor whose vehicle was pushed off a road and crashed during the storm. He said there are about 109 people in Kentucky who remain unaccounted for, including 81 in Hopkins County and 22 in Warren County.
Among others killed were eight night-shift workers at a candle factory in Mayfield, a city of about 10,000 people in western Kentucky. There were 110 employees inside the Mayfield Consumer Products facility when a twister closed in late Friday night, Mayfield Consumer Products CEO Troy Propes told ABC News.
"We feared much, much worse and, again, I pray that it's accurate," Beshear told reporters Monday morning, noting that "15-plus feet of wreckage," along with a lack of cellular service, made it difficult to determine how many individuals made it out of the destroyed facility alive.
On Monday evening, Louisville Emergency Management director E.J. Meiman told reporters that the factory's owners said they "verified that they have accounted for every occupant" who was present during the storm.
"We've also been meeting with all of our rescue experts that have been on the pile, and we have a high level of confidence there is nobody in this building," Meiman said, adding that the figure of eight fatalities at the facility hasn't changed.
One of the survivors, Kyanna Parsons, recalled hunkering down at the candle factory with her co-workers when the tornado hit. She said she felt a gust of wind and her ears popped. The lights flickered before going out completely and the roof of the building suddenly collapsed, she said.
"Everybody just starts screaming," Parsons told ABC News during an interview Sunday.
"I definitely had the fear that I wasn't gonna make it," she added. "It's a miracle any of us got out of there."
Mayfield Mayor Kathy Stewart O'Nan said she was at the scene of the destroyed factory the following morning. She recalled seeing first responders from Louisville, Kentucky's largest city, more than 200 miles away, "who had already gotten there, who had got in their trucks as quick as they could and come to help us."
"The offers from all over the United States are overwhelming," O'Nan told ABC News' Robin Roberts during an interview Monday. "We are so blessed with the state and federal support."
The mayor said her city lost its sewage treatment plant and a water tower, in addition to many homes and businesses. Mayfield still has no power, natural gas nor flowing water, according to O'Nan.
"The immediate needs of our city people and our responders are being met with just wonderful donations," she said. "But our infrastructure is damaged so severely that getting that up and running is our absolute greatest priority at this time."
O'Nan, who lives about four blocks from the center of the city's downtown area, said she knew from watching the weather forecast on the news last week that this storm would be "different."
"This was not a storm that us Kentuckians like to go out on the porch and watch roll by," she said.
When the twister touched down on Friday night, O'Nan said she took shelter in the basement of her home and waited there until she heard it pass overhead.
"That is a horrifying sound that I hope I never hear again," she said.
A few minutes later, O'Nan said, she got a call from the city's fire chief saying he couldn't get the firetrucks or ambulances out of the bay at the fire station because the doors wouldn't open. He ultimately had to attach a chain to his truck to pry the doors wide so firefighters and emergency workers could be dispatched, according to O'Nan.
"To watch them work tirelessly as they have during the last two days so far has just been heartwarming and heartbreaking at the same time," the mayor said.
"When I'm ever asked what's the greatest asset of our community, it is always our people," she added. "We've had small tragedies before and every time immediately the people bond together. I've seen that so much now, but we're joined by so many people from all across the commonwealth, all across the United States."
In the small town of Gilbertsville in Kentucky's Marshall County, about 35 miles northeast of Mayfield, entire neighborhoods were leveled. Wilbert Neil, an 88-year-old resident, returned to what was left of his two-story home with his 63-year-old son Jerry on Sunday and tried to salvage whatever valuables they could find. All of their belongings -- from clothing to vehicles -- were buried beneath debris. But they managed to find a safe with cash, their wallets, their firearms and a few spare clothes.
"Everything is destroyed," Wilbert Neil told ABC News while surveying the destruction. "We almost didn't make it."
The house was home for 21 years, Wilbert Neil said. He and his wife had bought it a year after they retired and it became the place where their children and grandchildren gathered during the holidays.
"This was the dream house for my wife," he said, tearfully. "She loved it. She'll never see it again."
Meanwhile, six people were killed in Illinois, where a tornado hit an Amazon facility. Four others were killed in Tennessee. There were two deaths reported in Arkansas and another two in Missouri, according to local officials.
During a press conference Monday, Amazon representatives told reporters that all six of the employees killed at the company's warehouse in Edwardsville, Illinois, had congregated in a part of the massive facility that was not meant to provide shelter from severe storms.
Illinois Gov. J.B. Pritzker said authorities are investigating "what exactly occurred" that evening at the Amazon warehouse and called the tornado that slammed into the building part of "an unexpected major, severe storm."
Amazon spokesperson Kelly Nantel said the Edwardsville facility had a designated shelter-in-place room, with no windows, on the north side of the building. Nearly all of the 46 employees working when the twister hit Friday night had gathered in the room after receiving tornado warnings, according to Nantel.
Nantel told reporters that seven of the employees, including the six who died, were working at the south end of the building that did not have a shelter-in-place room and huddled there as the tornado closed in. She said it was only a "matter of minutes" between the warning and the tornado strike.
She said the surviving worker huddled with that group was injured and is still receiving medical care.
John Felton, senior vice president of global delivery services at Amazon, said there was a "tremendous effort to keep everybody safe" on Friday, including the use of megaphones at the facility.
U.S. President Joe Biden declared a state of emergency in Kentucky on Saturday, ordering federal assistance to support the local response efforts. On Sunday night, Biden updated the declaration, making federal funding available to affected individuals in the Kentucky counties of Caldwell, Fulton, Graves, Hopkins, Marshall, Muhlenberg, Taylor and Warren. He also made it possible for residents to get assistance, such as grants for temporary housing or business repairs.
On Monday night, Biden approved emergency declarations for both Illinois and Tennessee.
The president will travel to Kentucky on Wednesday for a briefing from officials and to tour the damage in the cities of Mayfield and Dawson Springs, according to the White House. Biden received a briefing on Kentucky's storm damage in the Oval Office on Monday, after asking for a "detailed briefing" from his administration officials who were on the ground in Mayfield on Sunday.
"It's a town that has been wiped out, but it's not the only town, it's not the only town. That [tornado] path you see moves all the way up to well over 100 miles, and there's more than one route it goes," Biden told reporters Monday. "We're also seeing destruction met with a lot of compassion, I'm told."
The Kentucky governor said Biden called him three times on Saturday and that the president "has moved faster than we've ever seen on getting us the aid we need."
"We will welcome him here and we will thank him for his help and, sadly, we will show him the worst tornado damage imaginable -- certainly the worst in our state history," Beshear told reporters Monday.
Beshear has ordered flags to be flown at half-staff across Kentucky for a week in honor of those who were killed or impacted by the twisters. He asked other states to join in.
According to Beshear, more than 44,300 people from across the nation have donated over $6 million to Kentucky's relief fund: TeamWKYReliefFund.ky.gov. Meanwhile, Kentucky's first lady, Britainy Beshear, announced she is launching a Christmas toy drive on Tuesday to provide gifts to children who have been displaced by the devastation and "make this Christmas special for as many babies, kids and teens as possible who need our love and support more than ever."
Michael Dossett, director of Kentucky's Division of Emergency Management, praised the swift federal response during Monday's press conference, but cautioned that the restoration efforts on the ground "will go on for years to come."
"I can tell you from just being a veteran of now 17 disasters, it takes time to get wheels rolling," Dossett said. "This is a massive event -- the largest and most devastating in Kentucky's history."
ABC News' Patrick Doherty, Matt Foster, Ivan Pereira, Jakeira Gilbert, Max Golembo, Will Gretsky, Will McDuffie and Briana Stewart contributed to this report.