CHICAGO (AP) _All departing flights from Chicago's O'Hare and Midway airports were suspended for almost an hour Saturday when a traffic control tower was evacuated because of a possible gas leak.

Officials began smelling gas at Tracon tower in the Chicago suburb of Elgin shortly before 5:30 p.m., said Monique Bond, spokeswoman for the Chicago City Aviation Department.

The building was evacuated while engineers tried to determine what was causing the smell, Bond said.

No departures and only limited arrivals were permitted at either airport until Tracon was restaffed at about 6:30 p.m.

The source of the smell was still unclear, said Bond, who could not say how many flights had been delayed.