A local Chicago media message board reports:

"Less than two minutes later, the station was told by officials that the entire "crash" on King Drive was nothing more than a purposely faked stunt. The NBC-TV drama "Chicago Fire," which films entirely in the Chicago area, staged the crash for a rescue scene in an upcoming show, scheduled to air early next year. The producers of "Chicago Fire" placed small signs on posts & trees in the area, asking the local residents to NOT call 911 and that they were merely filming a TV show on location. They were doing so with permission from the City of Chicago and the Chicago Film Office.

However, outside of notifying local residents and the Chicago Fire Department, the media was not alerted in advance."

Video of the initial report is below: