The truck's two occupants have not been heard from since the crash and rescue crews pulled the tractor from the river and were working to get into the cab, said Lieutenant Jeff Lorentz of the Wisconsin State Patrol.
The truck had been headed west, but the eastbound lanes of I-94 have been closed at the site since just after the crash for the rescue crews. The interstate was open otherwise.
Roads in northwest Illinois had patches of ice and snow on Tuesday and road crews were bracing in northeast Illinois for the storm, which began dropping snow on Chicago near the middle of the morning rush hour.
Chicago was forecast to get 4 to 8 inches of snow, down about 2 inches from a previous forecast, according to the National Weather Service. The heaviest snow was expected Tuesday afternoon in the region, up to 1 inch per hour, and expected to snarl the evening rush hour.