A former student opened fire at a high school in southeast Turkey on Tuesday, wounding at least 16 people before killing himself, an official said.

The 18-year-old attacker, armed with a shotgun, fired randomly at a vocational high school in Siverek, Sanliurfa province, before hiding inside the building. He later killed himself with the same shotgun, Gov. Hasan Sildak said.

The attack left 10 students, four teachers, a canteen employee and a police officer wounded, Sildak said. While most of them were being treated in Siverek, five of the wounded teachers and students were were transferred to a hospital in the provincial capital because their conditions were more serious, the governor said.

The motive for the attack remains unclear. School shootings are rare in Turkey.

Earlier, media reports said all students were evacuated and police special operations units were deployed after the assailant refused to surrender.

“The individual was cornered inside the building through police intervention and died after shooting himself,” Sildak told reporters, adding that a “comprehensive” investigation into the shooting would be carried out.

Video footage showed dozens of students running out of the school toward the gate and onto the street. (CNN)