Police in New Jersey say an eighth-grade student plunged a knife into his school principal’s chest during a graduation rehearsal on Friday morning. The student, identified only as a 14-year-old male student of Union School, “ran across the gym and proceeded to thrust the knife, striking the chest of the principal several times,” the Rutherford Police Department said in a statement. The student then “dropped the knife and placed his hands in the air” before another teacher escorted him outside. No one else was injured in the incident, during which both the teenage suspect and the principal suffered non-life-threatening injuries. The teenager is facing aggravated assault charges, along with charges for unlawful possession of a weapon. Police have not commented on what might have prompted the attack but said they would have officers present at Wednesday night’s graduation ceremony in light of the incident.