At least 14 people been injured after a man rammed a car onto a sidewalk in the South Korean city of Seongnam, stepped out of the vehicle and began stabbing people at a shopping mall.

Thursday’s attack was followed by another stabbing incident on Friday at a high school in Daejeon, hours after South Korean President Yoon Suk Yeol alled for “ultra-strong” law enforcement measures in response to the pervious attack.

Cho Byeong-tae, an official at the Daejeon metropolitan police department, said the attack at Songchon High School left at least one teacher hurt.

At least five people were hurt by the car and nine others were stabbed during Thursday’s attack in Seongnam which happened in a crowded leisure district near a subway, according to Yoon Sung-hyun, an official from the southern Gyeonggi provincial police department.

Authorities arrested a 22-year-old man at the scene but did not offer any immediate information about a potential motive.

According to Park Gyeong-won, an official at Gyeonggi’s Bundang district police station, the suspect talked incoherently during police interviews and said he was being stalked by an unspecified source. The suspect’s family told police he had a history of mental illness.

While the suspect had purchased the two knives he used in the stabbings from a different shopping mall on Wednesday, there is not clear evidence he planned the attacks in advance, Park Gyeong-won said.

The attack was South Korea’s second mass stabbing attack in a month after a knife-wielding man stabbed at least four pedestrians on a street in Seoul, killing one person.

An official at Gyeonggi’s provincial fire department, Ha Dong-geun, said at least two of those who were wounded after the suspect drove the car onto the sidewalk were in a critical condition. Among the nine who were stabbed, eight were being treated for injuries seen as serious.

South Korea’s Kyunghyang Shinmun newspaper published a video on its website that it said was sent by a witness. The footage showed a man wearing sunglasses and a black hoodie walking up the mall’s escalator with an object in his hand.

The National Police Agency held an online meeting on Thursday with regional police chiefs to discuss ways to deal with stabbings and other attacks against random targets.