Tornadoes ripped across several U.S. states late Friday, killing more than 70 people in Kentucky, at least two at a nursing home in Arkansas and an undetermined number at an Amazon.com warehouse that was partially flattened in Illinois.

Kentucky Gov. Andy Beshear declared a state of emergency and activated the National Guard in the aftermath of storms that killed people in at least five states. President Joe Biden approved an emergency declaration for Kentucky, mobilizing federal assistance efforts for 15 counties.

Beshear said he was “now certain” that deaths will exceed 70 and may be more than 100, in a briefing in Graves County, where a candle factory collapsed with more than 100 people inside. No one has been rescued from the site at Mayfield since 3 a.m., mayor Kathy Stewart O’Nan told CNN, which reported that 40 people are still unaccounted for.

“This has been the most devastating tornado event in our state’s history,” Beshear said in a briefing Saturday.

>>RELATED: Kentucky hardest hit as storms leave dozens dead in 5 states

Biden’s declaration authorizes the Federal Emergency Management Agency to coordinate relief efforts in the stricken parts of Kentucky.

The National Weather Service warned that nighttime tornadoes “are particularly dangerous” since people may not be listening for severe weather warnings. Unlike hurricanes, the path of a tornado can’t be easily tracked in advance so giving timely evacuation orders is often unfeasible given their swift and often erratic path.

Damage will easily be in the hundreds of millions, if not $1 billion, said Chuck Watson, a catastrophe modeler with Enki Research.

Multiple additional incidents have been reported from four tornadoes that touched down in Kentucky and ripped across an area more than 200 miles long. Thousands of homes in the state were left without power.

In Illinois, part of the roof and wall collapsed at a large Amazon fulfillment site near Edwardsville, northeast of St. Louis, causing “confirmed fatalities,” according to the local police department.

Amazon’s CEO Andy Jassy tweeted the company is working with local officials and has been “closely monitoring the terrible situation.”

Graves County, in the state’s far southwest, bordering Tennessee, was the hardest hit among about 19 countries to experience storm damage.

Three storm-related deaths were confirmed in Tennessee, according to the state’s emergency management authorities.

At least two people were reported dead in Arkansas, where Gov. Asa Hutchinson said a tornado touched down in Mississippi County, north of Memphis, Tennessee.

In St. Charles County in Missouri, an 84-year-old woman was killed after a tornado ripped the family house off its foundation, the St. Louis Post-Dispatch reported.

A flash flood warning is in place across southern Kentucky, where tornadoes also stuck earlier this week, the National Weather Service said. The south fork of the Little River in Hopkinsville, Kentucky rose more than 10 feet from just after midnight to 6:30 a.m. local time.

Kentucky Sen. Mitch McConnell released a statement that said he is “praying for the lives lost and communities” impacted by the tornadoes and that he “will work with the entire Kentucky federal delegation to support” Beshear’s request for federal assistance.