Officials shut down all security checkpoint at Atlanta's Hartsfield-Jackson Airport after a "suspicious device" was detected in a screening machine.
The airport remained open while an airport explosive detection unit was called in, airport spokeswoman Felicia Browder said, but passengers not yet screened were unable to reach the gates for their flights.
Transportation Security Administration workers detected the suspicious item inside a bag just before 2 p.m., Browder said. She declined to comment further.
TSA spokeswoman Amy von Walter said a possible improvised explosive device had been detected at the airport's main checkpoint.
Hartsfield-Jackson Atlanta International Airport holds the title of the nation's busiest airport in number of takeoffs and landings, according to the Federal Aviation Administration. It wasn't immediately clear what impact the checkpoint shutdown would have on flights.