MURRYSVILLE, Pa. (KDKA/AP) – Doctors say a 17-year-old student who was among the most critically injured in a high school stabbing rampage outside Pittsburgh continues to improve after undergoing another surgery.

The University of Pittsburgh Medical Center said Sunday that the surgery went well. It didn’t mention the student by name, but says he’s still listed in critical condition.

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Spokesman Rick Pietzak says it’s the student’s fourth and last scheduled surgery.

Seventeen-year-old Jared Boger is among four students still hospitalized following Wednesday’s attack at Franklin Regional High School. He’s at UPMC Presbyterian, while three others are in critical condition at Forbes Hospital.

Within minutes of arriving at UPMC Presbyterian Hospital, Boger was in the OR for damage control surgery. The stab wound was two inches wide and penetrating nearly to his spine.

The knife had pierced his liver, diaphragm and major blood vessels.

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But one of Boger’s trauma surgeons, Dr. Juan Carlos Puyana, is convinced that the injuries would have been more lethal with a different weapon.

Sixteen-year-old Alex Hribal faces four counts of attempted homicide and 21 counts of aggravated assault in the attack. The school will resume classes Wednesday and teachers will return to work Monday.

The process of re-opening the school will be a gradual one, a process determined by a group of teachers, counselors, administrators and students, beginning with the return of the entire staff Monday morning.

Beginning Tuesday, students directly affected by the incident will be able to return and walk the halls or talk with teachers. The rest of the students will be able to return later in the day Tuesday.

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Lynne Hayes-Freeland