RUTHERFORD — A 14-year-old student repeatedly stabbed a middle school principal during graduation practice on Friday, police said.

Police arrested the teen at Washington School after getting a call about the attack at 9:30 a.m.

Police said Union School Principal Kurt Schweitzer was with his school's eighth graders rehearsing at Washington School when the teenager rushed across the gym and struck a folding knife several times into Schweitzer's chest. Schweitzer suffered non-life-threatening injuries, police said.

Police said the student then turned around, dropped the knife and placed his hands in the air.

A teacher escorted the student outside until police arrived.

Police did not say Friday afternoon whether they knew what motivated the attack.

The teen was charged as a juvenile with second-degree and third-degree aggravated assault and third-degree and fourth-degree weapons offenses. He remained in custody late Friday afternoon.

Because he is underage, police did not publicly identify the student.

Police said they will have "have a presence" at the graduation on Wednesday evening even though the department "is confident there are no remaining threats to any students or faculty."

Sergio Bichao is deputy digital editor at New Jersey 101.5. Send him news tips: Call 609-359-5348 or email sergio.bichao@townsquaremedia.com.