A 16-year-old boy who allegedly sold a stolen gun that was later fired at Highlands Intermediate School was arrested Wednesday for investigation of a firearms offense, police said.

Police Capt. Lester Hite said the boy is a former student of the school and sold the gun to a 14-year-old Highlands student. The 14-year-old was holding the firearm when it discharged on campus on May 23.

Police do not know how much money was exchanged for the gun.

Hite said the boys are acquaintances. The older boy hasn’t been in school since March, when he was asked to not return to an unidentified high school — not Pearl City High School — because he was not living in the district, Hite said.

Officers arrested the 16-year-old about 11:15 a.m. Wednesday on suspicion of a firearms offense and detaining stolen property. He was released pending investigation. Detectives are still investigating how the 16-year-old boy obtained the gun.

Officers recovered the .45-caliber Glock semiautomatic pistol after the gun went off May 23 in a stairwell at Highlands, while the younger boy was showing it to his friends. The older boy was not at the school when the weapon went off. Police believe the discharge was accidental.

Police said the bullet went through a 14-year-old boy’s jacket and hit a rock wall. Fragments from the wall hit the hand and thigh of a third 14-year-old boy, who was treated at the school and taken home by his parents. Paramedics took one student to a hospital after he complained of ringing in his ears.

The father of the boy who allegedly bought the gun told the Star-Advertiser that day that his son said he found the pistol on the Pearl City school’s campus and had never held a gun before. Police released the boy after arresting him for investigation of attempted murder.

The registered owner of the gun, a 47-year-old man, told police the gun was missing, but he had not reported it until police contacted him after the shooting.