Armed teen wearing mask runs through middle school classroom

ONTARIO, Calif. (FOX 11) - FOX 11 News has confirmed that the boy is a student at Deanza Middle School in Ontario. He was still in custody as students were let out for the day.

On Wednesday, the 13-year old put on a scary costume - but scarier than the mask, he was also carrying a semi-automatic gun.

He found an unlocked door and entered the classroom. Students initially didn't believe the gun was real.

The boy never fired the gun and then suddenly left the campus before Ontario Police arrived. Police found the boy, nearby with the costume and gun in his backpack.

"Thankfully, he did not choose to harm anyone. We're not even sure if that was his intent or if it was just to scare but at the same time." Sgt. Bill Russell of the Ontario Police Department said.

Students after the incident came to school to find beefed up security and went home with a letter to parents.

Police say, it is important to teach kids how to handle a gun, just as important that the gun be secured.

What might have been a Halloween prank could have been tragic, just like this.