One person was confirmed dead after a Thursday morning incident on outbound I-290 near the I-294 interchange in Westchester, where a bomb squad moved in on a vehicle and opened its doors.
Illinois State Police shut I-290 in both directions between 25th Avenue and Mannheim Road, and also closed the eastbound I-88 connection to I-290, snarling traffic through the area.
FBI and ATF agents joined state and local police at the scene, but authorities released no details on what happened or how many vehicles were involved.
Westchester police and the FBI said there was no known threat to public safety, even as federal and state investigators continued examining the vehicle.
The closure capped a chaotic morning on I-290 after an earlier Forest Park crash injured three people and a separate overturned vehicle spilled oil near Mannheim Road.