Gov. Pat Quinn declared a state of emergency after touring the region by helicopter. Some parts of the metro area had received 9-11 inches of torrential rain since Thursday night.
A sinkhole opened on Chicago's Southeast Side, swallowing three cars. Firefighters pulled one person from the 40-foot wide hole who was hospitalized, WGN-TV, Chicago, reported.
The third car slid into the hole after crews arrived at the scene. The local alderman said a 115-year-old eight-inch water main had burst undermining the street. Water and sewage service was cut in the affected area as crews debated how to remove safely the vehicles and repair the damaged infrastructure.
Officials said the Deep Tunnel, which holds 2.3 billion gallons of water, was filled and pressure in the sewer system sent water gushing through manhole covers.
The Chicago storm was part of a system over the middle Mississippi Valley, Accuweather.com reported.
Quinn activated the State Incident Response Center to speed up help to communities.
"I urge everyone to stay alert and avoid flooded areas," Quinn said in a statement. "Residents should tune in local TV and radio stations for updating information about closed routes or evacuations."
Two inches fell in 30 minutes in Lake County, north of Chicago, before the morning rush hour, an emergency management official told WFLD-TV, Chicago. He said the rain bands were like those of a hurricane causing flash flooding.
Hundreds of schools and Brookfield Zoo closed for the day and a sparse crowd of a few thousand fans turned out despite light rain for the 1:15 p.m. start of the Cubs-Texas Rangers game at Wrigley Field.
The early morning deluge closed three area expressways and the Chicago, Fox and Des Plaines rivers flooded low-lying areas, officials said. The Des Plaines, which was already over its banks, could crest at a record 3.5 feet above flood stage Friday. The Fox River was more than 2 feet above flood stage, the highest since widespread flooding in 2007, the Chicago Tribune said.
Water reached the roofs of cars on the South Side and in several suburbs, and hundreds of basements were flooded with as much as nine feet of brackish water. Several suburbs were sandbagging homes and businesses to try to keep flooding at bay.
Scores of people were evacuated from flooded neighborhoods and dozens of roads were impassable, littered with abandoned vehicles stuck in high water. A food truck set up shop on the side of a closed highway selling beef sandwiches to motorists stranded for more than three hours. Those who made it to work said their normal commuting time was doubled.
"We're expecting based on forecasts from the National Weather Service that we could approach or exceed major flood stages or even record flood stages at some locations," said Kent McKenzie, emergency management coordinator for Lake County.
In the suburb of Libertyville, part of a high school building sank a foot into the ground, fire officials said.
At O'Hare International Airport more than 500 flights were canceled and 150 more were delayed as much as 90 minutes. Metra commuter trains were delayed as much as 45 minutes, the Chicago Sun-Times reported.
The National Weather Service issued a flash flood warning for Cook and three other counties in Illinois and Lake County in Indiana. Commuters were advised to stay home.
The Chicago River had risen more than 6 feet, triggering a system that opened locks and pushes the water into Lake Michigan, an official with the Water Reclamation District said.
Flooding and mudslides have been reported in Iowa, and high winds in Texas. Low water crossings in Mayes, Okla., were underwater early Thursday after the area had received more than 3 inches of rain.
In Grove, Okla., the county's emergency management director, Robert Real, said three homes were destroyed by tornado-like winds, The (Oklahoma City) Oklahoman reported.
Real said several minor injuries were reported, but no one was hospitalized.