A 14-year-old boy is facing charges for allegedly attacking his school principal with a knife during graduation rehearsal.

Rutherford police say that the Union School principal was leading the eighth grade graduation rehearsals at the Washington School gymnasium when the teenager unexpectedly ran across the gym and struck the principal several times in the chest with a folding knife he had in his possession.

Police say that the teen then turned around, dropped the knife and placed his hands in the air. A teacher took the knife away and then brought the teen to the police officer assigned to the school.

The teen was not identified due to his age.

Paramedics came to treat the principal and the teen for injuries. Both are expected to be OK.

The teen was charged with aggravated assault and possession of a weapon.

No other injuries were reported.

It was not immediately clear what sparked the attack.