Smoke was reported in the Terminal Radar Approach Control (TRACON) at 1100 Bowes Road in Elgin at around 11:30am, reportedly causing sprinklers in part of the building to go off. Controllers were evacuated, and both airports were put on 'hold,' meaning no flights could land or take off. The 'all clear' was given just before 1pm.
Flights have resumed as normal, but activity at both airports will be disrupted for some time.
'Eyewitness News' has a crew at RFD and will have more on 'Eyewitness News' Local at 5 and 6.
Copyright 2016 Nexstar Broadcasting, Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.