A 12-year-old girl is in custody after a shooting at an Los Angeles middle school that police are calling unintentional. Four students were injured, but are expected to recover.

KTLA-TV reports the shooting Thursday morning at Salvador Castro Middle School in the city's Westlake neighborhood involved a semiautomatic weapon.

The victims are a 15-year-old boy, who was shot in the head, and a 15-year-old girl, who was shot in one of her wrists. Both are hospitalized.

Two other students, ages 11 and 12, suffered graze wounds and were treated and released. In addition, a 30-year-old woman suffered a minor injury in the chaos after the shooting

The 15-year-old boy was shot in the temple and is “extremely lucky” that the bullet missed vital structures, doctors say.

The 12-year-old girl has been booked for negligent discharge of a firearm and is in Los Angeles County Central Juvenile Hall.

Police didn’t disclose what led to the shooting, but said in a statement that the evidence "suggests that this was an isolated incident, involving the negligent discharge of a firearm, where innocent children and a staff member were unfortunately injured.”

The middle school shares a campus with Belmont High School.

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