Transportation Security Administration officials said a Maine man brought a loaded handgun to the Portland Jetport Friday morning.Officials said the 9 mm handgun loaded with 12 bullets was detected at a TSA security checkpoint.The man, who is from Hampden, told officers that he did not know the loaded gun was in his backpack, officials said.A TSA officer spotted the gun when the man's carry-on belongings went through the checkpoint X-ray machine.Airport police were contacted. They confiscated the gun and detained the man for questioning.Officials said the man was allowed to contact his wife, who drove to the airport to pick up the gun and take it home.This is the first gun found at the Jetport this year. TSA officers found three guns last year.Passengers are permitted to travel with firearms in checked baggage only if they are properly packaged and declared. Firearms must be unloaded, packed in a hard-sided case, locked and packed separately from ammunition, officials said.