An ambulance has arrived at a high school in Daedeok-gu, Daejeon on Friday after the stabbing incident happened. (Yonhap)

A man in his 20s was caught hours after stabbing a teacher at a high school in Daejeon on Friday, police said.

According to Daejeon Daedeok Police Station, the suspect entered the high school in Daedeok-gu around 10:03 a.m. and stabbed the teacher, aged 49, multiple times before fleeing.

Around 200 police force was mobilized to catch the suspect.

The man was nabbed some 8 kilometers away from the scene at around 12:20 p.m.

The suspect reportedly entered the school claiming he was an alumni and asked for the teacher who was in class the time. The incident occurred in a corridor, according to police.

The teacher, who sought for help after the attack, was moved to hospital and was undergoing surgery.

The school, which had begun the second semester the day before, had students stay in classrooms upon the incident until the suspect was detained.

The police are looking into motive behind the attack, believing the suspect knew the victim who was left in critical condition, according to reports. The suspect reportedly told the police he had been the injured teacher's student.

The incident occurred a day after a vehicle attack and stabbing rampage in Bundang, Seongnam, the day before, which left 14 wounded with two in critical condition.

The incidents have rattled the nation, with police vowing to mobilize “all possible forces” and reinforce inspections of any suspicious acts on streets.