A fire apparently set by an employee at a Chicago-area air traffic control centre led to the cancellation of more than 1,700 flights at the city’s two major airports, snarling air traffic across the United States, officials said.

Flights resumed at O’Hare International Airport, one of the world’s busiest, after a delay of about four hours, but there were bottlenecks across the entire air system that carriers expect to last through the weekend.

There were no indications that the fire was an act of terrorism and the blaze was quickly extinguished, authorities said. The Federal Aviation Administration said employees were evacuated from its control centre when the fire broke out. One person was treated for smoke inhalation.

Brian Howard, 36, who lives in the Chicago suburb of Naperville, was charged yesterday in US District Court in Chicago with one felony count of destruction of aircraft or aircraft facilities, prosecutors said.

Howard, who has worked at the facility in Aurora, near Chicago, for eight years, was recently told that he was being transferred to Hawaii, according to the complaint.

The suspect is a long-time employee of Harris Corp, which provides equipment and technical support for the FAA facility in Chicago and many others, US government officials said.

The FAA is still assessing the damage, which may be significant, but the agency hopes to restore air traffic to relatively normal levels over the next few days, they said.

According to an affidavit attached to the complaint, Howard could be seen on video entering the facility just after 5am dragging a black hard-sided suitcase.

About half an hour later a private message was posted to his Facebook account that said he was “about to take out” the control center and take his own life, the affidavit said. A relative forwarded the message to police.

Following the blood trail, paramedics found more knives and encountered Howard shirtless with cut wounds on his arms and saw him slicing at his own throat, the affidavit said.

Howard remains hospitalised and no court date has been set, prosecutors said. He would face up to 20 years in prison and a $250,000 fine if convicted on the charge.

The incident caused major delays at O’Hare and the domestic hub Midway International Airport, affecting flights from almost every state and routes with Europe, Asia and Latin America.

There were 1,755 flights into and out of the two airports that were cancelled by 8 pm CDT, according to tracking website flightaware.com, leaving thousands of travelers stranded.