(CNN) - Weary residents may get some good news Thursday as the monster storm system that already battered many Midwestern states and caused 12 deaths is expected to weaken.
The National Weather Service's Storm Prediction Center downgraded its outlook for severe weather from moderate to slight over the Southeast and Mid-Atlantic. It said there was only a 5% probability of tornadoes through Thursday morning.
The death toll from the enormous storm system that plowed through the Midwest and spawned more tornadoes as it moved east was at 12 late Wednesday, authorities said.
Hardest hit was Harrisburg, Illinois, a town that was thrashed by a pre-dawn EF4 killer tornado that packed 170 mph winds. Six people were killed in the southern Illinois city, many were injured or left with harrowing stories like Justin Hicks
"When we woke up half the roof was coming off the house," said Hicks. "We managed to get the small children in the closet and about the time the small children were in the closet my wife and I noticed the walls separating from the house."
Hicks' home was destroyed but he says it could have been much worse.
"We're very lucky to be alive" he said. " It happened so fast. I woke up to a chaos and I'm sure a lot of people woke up to chaos. I wasn't expecting it to be that bad."
The dead included four women and two men. The tornado had a preliminary rating of EF4, the second most powerful on the rating scale, according to the National Weather Service.
The twister 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, 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.
There were no reports Wednesday evening of anyone missing, the mayor said.
Harrisburg resident Caleb Cattivera said he rushed to his workplace early Wednesday only to find it gone. "I know a lot of people who live back near there."
Resident Les Winkeler said, "You just hoped your house didn't come down around you."
According to the sheriff's office, some 100 people were injured and between 250 and 300 houses were damaged or destroyed.
Among the structures hit was the Harrisburg Medical Center. CEO Vince Ashley said the tornado took out 80 feet of exterior wall, exposing patient rooms, and a significant portion of the roof.
A smaller tornado caused significant damage in the music resort city of Branson, Missouri.
Nearly 200 people were hurt across the region, officials said.
Two twisters were reported Wednesday night near Hodgenville, Kentucky. Winds in excess of 100 mph were reported in northwestern Alabama.
At least six counties in Kentucky suffered storm damage. A shaken and bruised Steven Vaught of Greenville, Kentucky, recounted how he and his two dogs tumbled when his trailer rolled several times down the hill. They all survived.
"It's a joy to be here. I don't know how I'm here," Vaught told CNN Nashville affiliate WSMV. "The good Lord just didn't call me. It wasn't my time."
An apparent tornado near Cassville, Missouri, left one person dead, the Barry County Sheriff's Office said. That person was thrown out of a mobile home, the Sheriff's Office said.
One death each has been reported in Buffalo and Puxico, Missouri officials said.
"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."
Missouri Gov. Jay Nixon, who declared a state of emergency, said the damage there was in at least the tens of millions, but there were no reported deaths. "We are confident that Branson will be back bigger and better than ever," Nixon said.
An EF2 tornado smashed at least seven miles of the city's commercial strip, leaving 33 people hurt, most with minor to moderate injuries.
The city's convention center and an attached Hilton were damaged, as was a portion of Branson Landing, a large shopping and entertainment complex.
City Administator Dean Kruithof said about five or six of the city's roughly 40 theaters were damaged.
"We have so many people who want crews in here to clean up, who want to start rebuilding," Kruithof said.
There were also three deaths Wednesday evening in Tennessee , authorities said.
CNN's Logan Burruss, Kara Devlin, Joe Sutton contributed to this report.