Millions from the Midwest to the southern Plains were under some form of tornado warning on Wednesday after multiple apparent twisters caused extensive damage in Illinois and Indiana.

Northern Illinois remains the highest risk, with a “moderate” tornado warning for 2 million people in cities south and east of Chicago, including Joliet, Peoria and Bloomington. A marginal risk extends all the way down to Texas and Tennessee.

A tornado emergency was declared in Knox, Indiana, on Tuesday, with the National Weather Service telling residents, “This is a life-threatening situation. Seek shelter now!”

On Tuesday, the parent thunderstorm that produced tornadoes in northern Illinois and northern Indiana persisted for over 7 hours, along a 200-mile path. According to the National Weather Service, there were eight reports of tornadoes between the two states on Tuesday, and two in Texas.

An elderly couple from Lake Village, Indiana, was killed in one of the tornadoes on Tuesday night, officials said on Wednesday. Several others were hospitalized from the storms, officials added.

Many areas were also hit by strong storms and heavy rain, with strong winds and hail the size of golf balls in the Chicago region. Flood warnings are in place along rivers in Illinois and Indiana.

Much of Indiana, northern Kentucky and western Ohio — including in Indianapolis, Evansville, Louisville and Cincinnati — are under a tornado watch until 12 p.m. ET. Approximately 67 million people are under the threat of severe storms from northern Pennsylvania down to the Gulf Coast.

More than 12,000 energy customers were without power across the Midwest and 23,000 across the Great Lakes region on Wednesday morning, according to PowerOutage.us.

NBC Chicago reported that there was significant, but so far unquantified, damage across northern Illinois and northwest Indiana, including to homes, other buildings, and roads.

Bob Wehrle, 60, told NBC News that he received an alert on his phone Tuesday night and, once he started seeing debris flying through the air from the storm, he took shelter in a basement utility room at his home in Kankakee, Illinois.

“Next thing I know, my kitchen is falling in on me,” Wehrle said. “The house is falling in, and I’m looking at the sky.”

Wehrle said he was not hurt in the storm, but it took his neighbors and family members about an hour to dig him out of the devastation. His wife, Margaret, was not home at the time of the storm because she was working at the hospital.

“The worst was there was a mini fridge in our house that ended up kinda on top of me, on my legs, and I couldn’t get it open to get water out of it,” he added, noting that he didn’t have to go to the hospital.