A routine day at the Hartsfield-Jackson International Airport in Atlanta took an unexpected turn on Sunday when the FBI was summoned to investigate a concerning discovery aboard a Frontier Airlines flight. A loaded gun magazine was found on the aircraft, prompting immediate action from authorities.

The incident unfolded just after 4:30 p.m. on Saturday. Officers from the Atlanta Police Department were dispatched to the airport following a report of the unsettling find near Gate C-6 in Concourse C, as detailed in a news release from the department.

The loaded magazine, containing ten hollow-point rounds and inscribed with the initials “K H,” was spotted by a passenger seated near 7A on the Airbus A320. This discovery came during the boarding process for a flight scheduled to return to Cincinnati.

In response to the incident, a Frontier flight attendant informed passengers that the plane would require a thorough investigation, as captured in a video by a passenger. This precautionary measure was necessary to ensure the safety and security of all those on board, according to a report by FOX 5 Atlanta.

A passenger on the plane recorded a Frontier flight attendant announcing the plane would need to be cleared for investigation. (FOX 5 Atlanta)

Officers coordinated with TSA, DOA, Frontier Airlines, Homeland Security and Atlanta Police K-9 units, and the aircraft was evacuated, according to the release.

After a thorough search by officers, no additional items of concern were found.

TSA screened all passengers a second time, and the flight departed safely just before 8 p.m., according to officials.

A Frontier plane was evacuated after a loaded gun magazine was found onboard. Eventually, the passengers were able to continue on their journey.  (FOX 5 Atlanta)

The FBI was notified of the matter, according to APD.

“No active threats were indicated at this time,” the agency wrote in the release.

A Frontier Airlines spokesperson told affiliate FOX 5 Atlanta the ammunition belonged to a member of law enforcement who was on an earlier flight.

A Frontier plane taking off at the Atlanta airport. (FOX 5 Atlanta)

“Customers were asked to deplane while a security sweep of the aircraft was conducted, along with additional passenger screening prior to the flight’s departure,” the airline told the outlet. “A subsequent investigation confirmed that the ammunition belonged to a law enforcement officer who was on an earlier flight on the same aircraft. The ammunition and magazine were taken into the custody of the Atlanta Police Department, and the property owner was referred to Atlanta P.D. to retrieve his items.”

However, an APD source told FOX 5 investigators have not confirmed who the magazine belonged to.

“I’ve heard of a lot of delays, canceled flights, but I’ve never heard of this before,” passenger Terry Foster told the outlet. “This is brand new.”

Another passenger, Janyia Davis, told FOX 5 she didn’t feel anyone was in danger, but “something bad could still happen.”

Frontier Airlines did not immediately respond to Fox News Digital’s request for comment.