An Alabama man caught with a loaded handgun in his carry-on bag at Boston’s Logan International Airport told Transportation Security Administration officers he didn’t know he had the weapon in his luggage and said a co-worker may have put it there, the TSA said in a statement Wednesday.

The 9mm gun loaded with five bullets was spotted by a TSA X-ray machine at a security checkpoint on Tuesday, the agency said.

The TSA contacted state police, who confiscated the gun and cited the man on a state weapons charge. The TSA did not release his name.

It was the fourth time this year the TSA has found a gun in a passenger’s luggage at Logan. The agency detected 18 last year.

Even travelers with concealed firearm permits are not allowed to bring guns onto airplanes in their carry-on bags, the agency said.