Arson attempt shuts Chicago airports

Hundreds of flights have been grounded at two major Chicago airports after an employee at an air traffic control centre lit a fire and tried to take his own life, officials say.

Flights into and out of the city's O'Hare International and Midway airports were cancelled as a result of the blaze at the Federal Aviation Administration's facility in Aurora, Illinois.

Almost 2000 flights were affected, including more than 1500 from O'Hare, the airport said, leaving thousands of frustrated passengers stranded.

According to a federal complaint, 36-year-old Brian Howard posted a message on his Facebook page saying he was going to "take out" the control centre and kill himself.

The complaint says Howard had worked as a contractor for about eight years and that he tried to start a fire in the basement, apparently using a gas can and towels.

Paramedics rescued Howard as he was in the process of cutting his own throat, the complaint states and he was taken to an area hospital.

Authorities said the incident was not being treated as terror-related.

A senior adviser to President Barack Obama said federal authorities had joined the probe into the fire, as delays and cancellations snarled air transit across the country.

"An investigation is under way between federal, state and local authorities and we will be hearing more from them as they have results," the spokeswoman said.

By Friday evening local time, international flights were resuming, the airport said.

The FAA has not said when normal operations would resume.

"Chicago airspace is almost completely empty due to fire at Aurora Air Traffic Control," Flightradar24 tracking website said.

The FAA released a statement on Friday saying that the fire occurred shortly before 6:00am local time in a basement telecommunications room and the aviation radar facility was evacuated.

Authorities said some operations of the centre, which is responsible for guiding high-altitude air traffic into and out of the airports, would be taken over by other air traffic sites.

O'Hare, the second largest US airport, handles more than 67 million passengers each year.

* Readers seeking support and information about suicide prevention can contact Lifeline on 13 11 14 or Suicide Call Back Service on 1300 659 467.