The attack happened around 8:40 a.m. in the city some 110 kilometers south of Seoul, as the second-grade high school student began stabbing people inside a classroom.
The victims were taken to hospitals with minor to serious injuries to the chest, abdomen and other areas, and are being treated there. None of them are in critical condition, officials said.
The student jumped into a nearby reservoir after the attack but was rescued and also transferred to a hospital.
The school has convened an emergency faculty meeting to discuss the incident and his possible motive, an official at the provincial education office said.
Police are also questioning school officials.
AzVision.az
More about: SouthKorea
