Police arrested a 13-year-old girl for allegedly stabbing a 13-year-old boy at a school in St. Paul on Monday.

Paramedics took the teen to Regions Hospital with a non-life-threatening injury to his stomach, said Sgt. Mike Ernster, a St. Paul police spokesman. A licensed school nurse provided first aid at the scene.

Officers were called to the stabbing at Community of Peace Academy, a preK-12 charter school in the Payne-Phalen area, about 11 a.m. Monday.

Police said they are investigating what led to the incident.

David Núñez, the academy’s executive director, said staff “mobilized to defuse the situation immediately,” they called 911 and the school went into lockdown. The academy is on Magnolia Avenue between Arkwright and Edgerton streets,

The student left school grounds and was soon apprehended by St. Paul police, according to Núñez.

The 13-year-old year girl was arrested on suspicion of aggravated assault and the Ramsey County Attorney’s Office charged her Tuesday with second-degree assault. The weapon was described as a folding knife, Ernster said.

The school’s social worker team is providing crisis counseling and support to students who witnessed or heard about the incident, and parents were notified of what happened, Núñez said.