A fire at a suburban Chicago air traffic control facility that shut down the city's two airports Friday was intentionally set by a contract employee, police said.

The early morning fire forced the evacuation of the control center in Aurora, about 40 miles west of downtown Chicago. Emergency crews found a man in the basement with a self-inflicted wound and took him to a hospital.

The man was a contract employee of the Federal Aviation Administration, said Aurora Police Chief Gregory Thomas.

He said it was not a terrorist act and that the investigation was being run by the FBI, the Bureau of Alcohol, Tobacco, Firearms and Explosives and local police and fire departments.

All flights in and out of Chicago's two airports were halted Friday morning.

The center was evacuated, Federal Aviation Administration spokeswoman Elizabeth Cory said, and management of the region's air space was transferred to other facilities.

An employee of the facility was treated at the scene for smoke inhalation and the fire was extinguished by 7 a.m.

By 8:30 a.m., more than 580 flights at O'Hare and Midway had been canceled, according to aviation tracker FlightAware.com. FlightAware.com CEO Daniel Baker said the number of cancellations and delays are expected to rise considerably over the next few hours. Southwest Airlines suspended all flights at Midway until noon, according to the Chicago Department of Aviation.

At O'Hare's Terminal 3, long lines formed at ticket counters as airlines continued to check in passengers.

Waiting by an American Airlines counter, Jon Sciarrini said his homebound flight to Dallas had been delayed and he didn't know whether he should wait or try to arrange another flight.

"It's pretty frustrating - a little like being in purgatory," the IT specialist said.