The U.S. air transportation system got a big jolt Friday when a fire at the Chicago air hub's air traffic control section affected air traffic in and out of the area's O'Hare and Midway airports.

More than 850 flights through Chicago were canceled with more expected to be cancelled throughout the day as two of the nation's busiest air facilities were closed. Flights were resuming on a case-by-case basis during the afternoon, but the traffic slowdown affected airports nationwide.

Like Us on Facebook

Chicago is a major hub for airlines and passengers, many of whom switch planes and use the airports  for key connecting legs of journeys. While no serious problems were in play, Chicago delays and cancellations were causing problems from New York to Seattle and all points in-between.

The fire took place at the key Chicago Air Route Traffic Control Center. The center at Aurora, Ill, about 35 miles from the downtown Chicago Loop, was evacuated as emergency personnel rushed in to deal with a basement blaze. While initial reports had people concerned about possible terrorism, the 5:45 a.m. fire was caused by another source, authorities said.

Aurora Police Chief Greg Thomas said authorities found a man with a self-inflicted gunshot wound in the facility basement and transported him to a nearby hospital. Police believed the fire was related to "a local issue with a contracted employee and nothing else," he said.

Faint consolation indeed, as up to 30 air traffic control center workers were evacuated from the center that is responsible for keeping airlines on point and safe in the skies. Ripple effects from the blaze resonated throughout the nation's highly connected air transportation system.

American, Delta, Southwest, United and other major air carriers reported hundreds of flight cancellations and e-delays through the day although some airports were less affected than others. Many airports reported 10 times the number of cancellations than on a normal day.

There was no word when normal flight patterns and airport traffic would resume.

TagsO'Hare field, Midway field, air traffc control fire, Chicago, airports, air transportation, air traffic control center, Airlines, southwest, delta, united, air traffic delays