One woman was said to be fighting for life in Naperville, where 16 homes were left “uninhabitable” and dozens of other homes were damaged when the twister touched down after 11pm on Sunday.
More than 120 other reports of property damage had been received by 5am on Monday (11am BST) in the suburb about 25 miles west of downtown Chicago. City spokeswoman Linda LaCloche said those were expected to grow as residents surveyed the storm damage. About 450 power outages were reported.
"We're lucky that it wasn't worse," she said Monday morning. "We have a lot of utility poles and electrical wires down, and tree damage."
Video showed several large trees downed and damage to homes and vehicles in the path of the storm. Some gas leaks were reported in Naperville, and crews went door to door shutting off lines, she said.
Officials in the nearby village of Woodridge said a tornado touched down late on Sunday and a damage assessment was underway. There were no reports of significant injuries in the community, but people were urged to avoid the area due to downed power lines and trees.
The storm destroyed the second floor of Bridget Casey's Woodridge home. She sat in a lawn chair in the driveway before sunrise on Monday.
Her son, Nate Casey, 16, said he was watching TV when the storm swept through and he raced to help his mother get his three younger siblings to the basement.
"I just heard a loud crash and I'm thinking, `Oh, what are my brothers up to?' I go look and I see the sky, and then I hear my brothers screaming from the room," he told the Chicago Sun-Times.
Matt Friedlein, a meteorologist with the National Weather Service in Romeoville, Illinois, said a team from the weather service would be surveying storm damage on Monday to determine the reported tornado's strength and its path. He said the same storm is believed to have rolled through Naperville, Woodridge and Darien, and may have also caused damage in Burr Ridge, about 20 miles southwest of Chicago,
"If there were no fatalities - and there haven't been any reported to us - that's great news considering the population of the area, the level of damage and the time of day, after 11pm when many people may be asleep," he said.