A gun passed through security at Hartsfield-Jackson International Airport without being detected and was taken by a passenger on a Delta Air Lines flight to Japan, according to officials.

The passenger flew from Atlanta to Tokyo's Narita International Airport, and disclosed what occurred to Delta, which notified the Transportation Security Administration.

TSA acknowledged that "a passenger did in fact pass through a standard screening TSA checkpoint with a firearm at Hartsfield-Jackson Atlanta International Airport on January 2. TSA will hold those responsible appropriately accountable."

The incident happened amid the partial federal shutdown that has left TSA officers working without pay since Dec. 22.

TSA said the checkpoint was fully staffed at the time, and said the rate of unscheduled absences that day, at 5 percent, was the same as a year ago.

Guns are supposed to be detected when TSA officers review X-ray images as passengers and their bags go through the checkpoint.

The agency said “standard procedures were not followed,” and the gun was not discovered.

Amid the federal shutdown, many travelers are concerned about air travel safety, according to a survey by Airfarewatchdog.com. The site said it polled 1,000 travelers and found that 62 percent are concerned about air travel safety in the wake of hundreds of TSA officers calling out sick. The survey also indicated that 47 percent of travelers think airlines should be required to pay for private security during times of a government shutdown.

Even during normal operations, TSA has had other instances of failing to stop guns from getting through security.

In 2015, TSA investigated a report that a loaded semi-automatic handgun was carried by a passenger on a Southwest Airlines flight from Atlanta to Chicago and was not detected at the security checkpoint at Hartsfield-Jackson. Incidents of missed guns at other airport security checkpoints around the country have also been reported over the years.

Several years ago, TSA was criticized for failures to detect mock explosives and weapons during tests, and ended up retraining airport screeners around the country.