A freshman at Falmouth High School was arrested yesterday morning when police and school officials found the boy carrying a pistol. School officials called police to report that a 15-year-old student was bragging that he was carrying a gun in school. Officers arrived and removed the boy from a classroom. The boy admitted to carrying a .38-caliber pistol, police said. The gun was not loaded, and the boy did not have any ammunition, police said. An initial investigation found that the boy took the gun from a relative without permission. The relative’s license to carry firearms has been suspended, pending the result of a full investigation, police said. The student, whose name was not released, was booked on charges of carrying a firearm on school grounds and carrying a firearm without a license. He was arraigned in the juvenile session at Falmouth District Court yesterday morning and released on his own recognizance.