PORTLAND, Ore. (KOIN) — The Transportation Security Administration announced Tuesday that it is investigating how Washington state Sen. Jeff Wilson made it past TSA security with an unloaded handgun in his carry-on luggage at the Portland International Airport on Oct. 21.

The Longview lawmaker said that he unknowingly took the gun through PDX security before boarding a flight to San Francisco International Airport. From there, Wilson said that he boarded a connecting flight from SFO to Hong Kong, where he discovered the gun in his briefcase while searching for a stick of gum. Wilson was subsequently arrested after reporting the gun to Chinese customs officials after landing in Hong Kong.

“TSA is aware that a passenger on a flight departing from PDX Saturday passed through security and traveled with an unloaded firearm in his carry-on bag,” a TSA spokesperson told KOIN 6. “The individual was arrested upon arrival in Hong Kong. TSA takes this situation very seriously and is currently investigating the circumstances.”

The TSA said that it will use closed-circuit TV and images from screening equipment to determine how the gun made it past PDX security. Following the investigation, the federal agency said that it may take “appropriate corrective action” and give employees additional training.

“Firearms are not permitted in the secure area of airports and represents an expensive mistake for those who are stopped at checkpoints with firearms in their possession,” the TSA said.

So far, TSA officers have found 43 guns at PDX security checkpoints in 2023. The agency said that TSA checkpoints catch people attempting to pass through airport security with guns nationwide. Penalties for bringing a gun through a TSA checkpoint can include a $15,000 fine and a five-year ban from TSA PreCheck lines.