The van belonged to the Salvation Army's halfway house in Chicago, said Robert Cotner, director of development. He did not know where it was coming from or where it was going.
Capt. Dave Sanders, a state police spokesman, said the Salvation Army's minivan was struck broadside by the tractor-trailer when the minivan crossed the highway. There was no immediate indication what caused the southbound van to veer from the road around 9:40 a.m. CT.
Snow had been falling throughout the morning, but the road was clear with no snow buildup, officials said. The crash happened on Interstate 55, a short distance from its intersection with Interstate 80.
The driver of the van was in critical condition at Provena St. Joseph Hospital, spokeswoman Paula Sellergren said. The driver of the tractor-trailer was in good condition, she said.
There were few details immediately available about the victims. Salvation Army spokesman Richard Grozik said the van is used to take families to visit prisoners.
"We're just devastated by this news and we're trying to sort through it," he said.
At the Salvation Army office in Chicago that owned the van, Kenneth Allen cried as he awaited word about his sister, Betty Allen. She was taking one of the organization's vans Friday to see her husband at the state prison in Pontiac.
"I'm praying she wasn't on that bus," he said.
In Iowa, a charter bus full of Iowa City students on a ski trip collided with a car Friday, killing at least two people in the car and injuring nine people on the bus, none seriously.
The crash happened around 9 a.m. on U.S. Highway 151 northeast of Cedar Rapids in the eastern part of the state. As with the Illinois crash, it had been snowing Friday morning, but it was not immediately clear if weather was a factor in the crash.
Snow was falling in a band across the central U.S. at the time of the mid-morning crash. Police in St. Louis reported several traffic accidents, some involving school buses, but no major injuries. Police in Louisville, Kentucky, also reported weather-related traffic accidents.
©MMI Viacom Internet Services Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press and Reuters Limited contributed to this report