In Gary, Ind., a flood-fighting drill scheduled for Friday was canceled — because of real flooding. Sandbagging operations were under way along the Little Calumet River.
Flash flooding was common. In Utica, Ill., the fire department evacuated a mobile home park. In Marshall County, Ill., boats were needed to rescue trapped morning commuters.
In Ava, Mo., a school bus carrying several children stopped because of water on the road. The driver turned around to go back, only to find flooding behind him, too. The driver and kids waited at a nearby home until help arrived.
Perhaps the storm's most bizarre scene came in Chicago, where a massive sinkhole opened and swallowed two parked cars and one that was driving through. The driver was hospitalized but was expected to survive.
Flooding from all-night rain storms forced authorities to close sections of several major expressways around Chicago, canceled classes at some schools and scrapped around 550 flights at O'Hare International Airport.
The storm-swollen Chicago River was being allowed to flow into Lake Michigan, in part to relieve sewer backups. Meanwhile, workers were furiously filling sandbags and putting up barricades along the Chicago River's north branch. The river was diverted away from the lake more than a century ago to keep pollution out of the lake, the source of the city's drinking water.
Winds, possibly from a tornado, damaged dozens of homes in Spavinaw, Okla., injuring one person. Another twister damaged a few buildings near Paris, Mo. High winds also blew two tractor-trailers off a highway near Monroe City, Mo.
In Kansas, large hail was blamed for an accident that injured six high school students and their teacher. The Kansas Highway Patrol said the wreck happened Wednesday on Interstate 70 near Russell. The group was returning to school from an art exhibition when the teacher lost control of the SUV and struck a car.
The U.S. Nuclear Regulatory Commission said a lightning strike knocked out power to a northern Illinois nuclear plant for several hours Wednesday night, but emergency generators kicked in to keep the site running. Exelon Generation said reactors will remain offline until safety checks and procedures are completed.
Up to a foot of new snow was expected in northern Minnesota. Duluth has already received 24 inches of snow this month, and the additional snowfall could push it past the April record of 31.6 inches set in 1950
Snow and ice forced closure of sections of Interstate 70 and Interstate 25 in Colorado. The Wyoming Department of Transportation warned drivers to watch for black ice.
The snow didn't bother 63-year-old Bill Zubke, a retired motivational speaker who was relaxing in the lobby of a downtown Sioux Falls, S.D. Zubke, from Watertown, S.D, described the unpredictable weather as "just April in South Dakota," though temperatures ordinarily reach into the 60 this time of year.
"We're South Dakotans," he said. "We can handle it."
Keyser reported from Chicago. Associated Press writers Maria Sudekum in Kansas City, Mo., Dirk Lammers in Sioux Falls, S.D., and Tammy Webber in Chicago contributed to this report.
Watch The Associated Press' video here: http://bit.ly/13rcncw