A passenger carries a firearm through TSA screening at Atlanta onto Delta flight.

Axar.az reports citing CNN.

A traveler carrying a firearm boarded a flight from Atlanta Hartsfield-Jackson International Airport and flew to Tokyo Narita International Airport on January 3, according to a statement from the Transportation Security Administration.

"TSA has determined standard procedures were not followed and a passenger did in fact pass through a standard screening TSA checkpoint with a firearm at Hartsfield-Jackson Atlanta International Airport on the morning of January 3," the release states.

Delta Airlines also issued a statement to CNN, saying that "upon the customer's disclosure, the airline reported the incident to the TSA."

The security breach came two weeks into the government shutdown, during which TSA agents have been required to work but have not received paychecks. CNN first reported on January 4 -- a day after the breach -- that hundreds of TSA agents from at least four major airports had called in sick.

However, the TSA dismissed suggestions the government shutdown contributed to the security lapse and said a normal amount of staffers were working that day.