A fourth-grader fired a semiautomatic handgun inside an elementary school as he was showing it to a friend, Linden police said.
Lt. Raymond Tyra said no one was injured in the incident, which occurred at School Number 2 at about 3:15 Wednesday afternoon.
A 10-year-old boy was showing the .38-caliber gun to his friend in a coat closet when the weapon went off. A bullet passed through the wall and into the classroom next door, where it lodged in a wall.
Tyra said most of the kindergarten to fifth-grade students who attend the school had gone home before the incident.
Police officers also recovered the gun and secured the school.
Investigators tried to determine how the child got the weapon.