June 11 (UPI) -- The death toll in a school shooting at an Austrian high school rose to 10 after a female teacher died of her injuries in the hospital.

Police in the city of Graz told CNN early Wednesday that nine of those killed were students at Dreierschutzengasse school, aged between 15 and 17. Interior Minister Gehard Karner said six of the deceased were girls and three were boys and that 12 students were in the hospital, some of them in a serious condition.

A 21-year-old former student, believed to have carried out the attack using a shotgun and a pistol that authorities believe he acquired legally, died in a school restroom from a self-inflicted gunshot.

Police said they found suicide messages on video and in a written note and safely removed a non-functioning pipe bomb during a search of his home in the Graz area.

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