PHILADELPHIA, Pennsylvania (BNO NEWS) — Two men have been arrested after smuggling a gun on board a U.S. Airways flight at Philadelphia International Airport on Thursday morning, FBI officials told BNO News.

Authorities ordered a passenger plane to return to the gate after a passenger reported a concern about a carry-on bag to the Transportation Security Administration (TSA), a U.S. Airways spokesperson said. Officers then boarded the plane and discovered a handgun in the bag, resulting in the arrest of two people.

One of the people arrested was a U.S. Airways employee, who reportedly helped the passenger smuggle the gun on board, Special Agent J. Klaver said. “The investigation is ongoing but the threat posed by this isolated incident has been contained,” he said.

The flight involved was U.S. Airways flight 1195 which was scheduled to depart to Phoenix, Arizona this morning. “Safety and security is our first and foremost priority in everything we do,” a U.S. Airways spokesperson told BNO News in a written statement. “We are cooperating with investigators fully and take security considerations very seriously,” it added.

The spokesperson refused to provide further comment, saying it was not appropriate at this time as the investigation is still ongoing.

According to Phoenix-based KPHO-TV, it was a 9mm handgun and reports say bullets were found in the bag. Special Agent Klaver said it is unclear what their intend was but did say it does not appear to be terrorism-related. “We are still trying to sort through all the pieces,” he said.