(CNN) -- A powerful storm system that spawned suspected tornadoes -- and at least one with winds estimated at 170 mph -- left destruction and death in its wake as it pushed through the Midwest on Wednesday, leaving at least nine dead and more than 100 injured, authorities said.
Other possible tornadoes are expected into Wednesday evening as the storm pushes toward the Mid-Atlantic region, according to CNN meteorologist Sean Morris.
Such activity was possible in northern Alabama, extreme north Georgia, southern and eastern Kentucky, northern Mississippi, western North Carolina and much of Tennessee, he said.
In addition to possible tornadoes, the storm itself will carry thunderstorm winds as strong as 80 mph.
Among the hardest hit cities was Harrisburg, Illinois, where at least six people were killed, according to the governor's office. The dead included four women and two men.
The tornado that hit Harrisburg was preliminarily rated an EF4 -- the second most powerful on the rating scale -- according to the National Weather Service. A report indicated the tornado had winds estimated at 170 mph.
The number of fatalities in Harrisburg could rise in the wake of the suspected twister, which appeared to have been on the ground for several miles, said Mayor Eric Gregg. The path of destruction was about three or four football fields wide, he said.
The scene in the southern part of Harrisburg, in southern Illinois, was one of debris and collapsed houses. Commercial and residential buildings were crushed. A tractor-trailer could be seen laying on its side, off the highway.
"When the sirens were going on this morning ... it was eerily quiet. I had a gut feeling something was wrong," Gregg told reporters.
"We will rebuild this city. This will make us stronger." Gregg said.
According to the sheriff's office, some 100 people were injured and between 250 and 300 houses were damaged or destroyed. Some 25 businesses were also damaged or destroyed, the sheriff's office said.
"It's like nothing I've ever seen, and something I don't care to see again," Gregg said.
Among the structures hit was the Harrisburg Medical Center.
The suspected tornado sheared off part of the building's southern wall, leaving several patients' rooms exposed, as well as some offices, said hospital worker Jane Harper.
Luckily, hospital staff had enough time to move those patients to the better-protected center of the building before the suspected twister struck, she said.
"I've had my share of disasters, but never seen a tornado like this, that's for sure," she said.
As of Wednesday afternoon, the storm was threatening Kentucky, among other states.
Several counties in the Bluegrass State reported storm damage, but no fatalities were immediately reported.
"We can't confirm there was a tornado, but we have reported sightings and they have actually seen some video of what appears to be a tornado," Kentucky Emergency Management spokesman Buddy Rogers said.
That possible tornado struck in McCracken County, where five injuries were reported, one critical, Rogers said.
At least six counties in the state reported structure damage. The Kentucky National Guard activated 30 soldiers in LaRue County to assist.
There deaths were reported in Missouri as a result of the storms, Gov. Jay Nixon told CNN.
A woman was killed overnight in Dallas County, Missouri, the coroner there said, without giving further details.
An apparent tornado near Cassville, Missouri, left another person dead, the Barry County Sheriff's Office said. That person was thrown out of a mobile home, the sheriff's office said.
The resort community of Branson was also hit.
"I woke up this morning and looked outside and saw houses were destroyed," said Steven Scharmanzer in Branson. "I've never seen anything like this in the 20 years I've lived here."
Nixon said the damage there was in at least the tens of millions, but there were no reported deaths. A significant area of the business district was damaged, he said.
"We are confident that Branson will be back bigger and better than ever," Nixon said.
Kansas was hit Tuesday night, and Gov. Sam Brownback declared a state of emergency for the tiny town of Harveyville, about 20 miles southwest of Topeka. Emergency teams combed the community to assess damage after the National Weather Service confirmed a tornado had struck the city.
Some homes and a church were damaged, and there were numerous reports of trees and power lines down throughout the area, according to the Kansas Adjutant General's Department.
At least one person was critically injured and transported to a hospital in Topeka, while four others were briefly trapped in a structure.
There were also reports