US Vice President Joe Biden has supported states hit by a swarm of deadly tornadoes that destroyed homes, leveled businesses, and left at least 100 people thought dead, Al-Jazeera reported.

Biden, who described the tornado outbreak as possibly "one of the largest" in history, approved an emergency disaster declaration for the hardest-hit state of Kentucky on Saturday, where at least 22 people have been confirmed dead.

According to weather forecasts, twisters blasted apart a candle factory in Mayfield, Kentucky, ripped through a nursing home in neighboring Arkansas, and killed at least six workers at an Amazon warehouse in Illinois.

Governor Andy Beshear of Kentucky stated that the tornado outbreak was the most catastrophic in history. He claimed approximately 40 workers had been evacuated from the candle factory, which was turned into a mound of wreckage after being destroyed to a pile of rubble.

Finding anyone else alive beneath the debris would be a "miracle," Beshear said.

"The devastation is unlike anything I have ever witnessed in my life, and I am at a loss for words," Beshear stated during a press conference. "It's very likely that over 100 people will be killed here in Kentucky."

According to video and photographs shared on social media, brick buildings in downtown Mayfield were destroyed, with parked automobiles practically buried beneath the debris.