This Is What It Looks Like When You Shut Down a Major Airport

PHOTO: Flightradar24 posted this screenshot to Twitter Sept. 26, 2014, with the caption, "Screenshot from http://www.flightradar24.com showing flights over Chicago and US flying on 10,000 feet and above."Play@flightradar24/Twitter
WATCH Chicago Traffic Control Center Fire Stops Flights

Air traffic around Chicago has come to a halt because of a fire at an FAA Air Traffic Control Center in Aurora, Illinois.

Police said the fire was extinguished but there is an ongoing investigation.

PHOTO: Flightradar24 posted this photo to Twitter on Sept. 26, 2014 with the caption, Still no air traffic above 10,000 feet in Chicago ATC. 240+ flights canceled to/from OHare & Midway airports. @flightradar24/Twitter
Flightradar24 posted this photo to Twitter on Sept. 26, 2014 with the caption, "Still no air traffic above 10,000 feet in Chicago ATC. 240+ flights canceled to/from O'Hare & Midway airports."

As of 9:05 a.m. ET, Flightaware.com reported 446 cancellations to and from O'Hare and Midway airports, 13 percent of their daily schedule, and 107 delays. Flightaware.com said the number of cancellations and delays will “rise considerably” over the next few hours.

Contract Employee Eyed in Fire That Grounded Chicago Flights

ABC News' Matt Hosford contributed to this report.