Ammon News - Tornadoes ripped across a wide swath of central and southern United States on Wednesday, destroying homes and businesses and bringing down power lines and trees.

The National Weather Service said there had been at least 15 reports of tornadoes in at least four states by late Wednesday.

Eight people have been injured across Kentucky and Arkansas, including one critically injured in Kentucky's Ballard County, local officials said.

Late Wednesday, Arkansas Governor Sarah Huckabee Sanders declared, opens new tab a state of emergency across the state due to the storms, which also brought hail and torrential rain.

The NWS said millions of people were under alerts for tornadoes and flash floods and that dangers would continue into early Thursday.

Violent storms are forecast to ravage the country for several days, the NWS said, with Wednesday just "the beginning of a multi-day catastrophic and potentially historic heavy rainfall event."

"The word for tonight is 'chaotic,'" said Scott Kleebauer, a NWS meteorologist. "This is a large expanse of storms migrating slowly to the east, stretching from southeast Michigan down into southeastern Arkansas."

The town of Nevada, Missouri, was hit by a tornado. Writing on social media, the state's Emergency Management Agency said it caused "major damage to several businesses, power poles were snapped and several (empty) train cars were flipped onto their sides by the powerful storm!"

The NWS issued tornado and flash flood warnings for parts of Missouri, Arkansas, Tennessee, Mississippi, Indiana, Illinois, Kentucky and Oklahoma.

It called the rain threats for Arkansas, Missouri, Tennessee and Mississippi in the coming days a "generational flood event" with some locations forecast to see as much as 15 inches (38.1 cm) of rain by the weekend, which could cause rivers to burst their banks and cause "catastrophic river flooding."

More than 400,000 customers had their power knocked out across the storm-hit area, according to PowerOutage.us.