Police were questioning an unidentified suspect in his 20s who was arrested at the scene. Police officials did not immediately comment on any potential motive for the attack.
Photos from the scene showed forensic units examining the halls of the AK Plaza, where the stabbings took place. A white Kia hatchback with a broken front window and ruptured front tire could be seen on a sidewalk near the Seohyeon subway station.
The National Police Agency held an online meeting Thursday with regional police chiefs to discuss ways to deal with stabbings and other attacks against random targets.
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During the meeting, National Police Agency Commissioner General Yoon Hee-keun described the attack as “virtually an act of terrorism”.
Officials discussed increasing nighttime patrols in leisure districts and other crowded areas and strengthening security camera surveillance, according to the agency.
Last month, a knife-wielding man stabbed at least four pedestrians on a street in the capital, Seoul, killing one person, police said.