South Koreans shocked after back-to-back stabbing rampages

"I've always been telling my kids to be careful when they go abroad due to gun fears but now I'm more scared of being in South Korea," Lee Young-ja, a 78-year-old Seongnam resident who fled after hearing people screaming during Thursday's incident, told Reuters.

Another resident in the area, Choi Jun-ho, 26, said he was staying extra vigilant on his way to work on Friday morning, near the mall where the stabbing took place.

"It's unnerving," Choi said. "Something like this could happen right next to me."

President Yoon Suk Yeol called the incident an act of terrorism against innocent citizens and ordered police to mobilise all available resources to ease public concerns.

On social media, a list of copycat attack threats were circulating.

"I've been telling my families and friends to stay home," a 31-year-old Seoul resident said. She spoke on condition of anonymity due to fears for her safety.

"I hope people posting those threats all get tracked down and harshly punished."

Police Commissioner General Yoon Hee-keun on Thursday warned South Koreans to be on guard for such attacks and told officials to be vigilant.

Experts said there was a risk similar crimes could follow, and urged authorities to swiftly analyse patterns in recent rampage crimes to come up with countermeasures.

"The suspects not having clear motives doesn't necessarily mean that there's no way to prevent these crimes," Kim Do-woo, a police science professor at Kyungnam University, said.

For example, police should closely monitor and proactively intervene when there's any reports of suspicious acts at crowded public areas as both of the stabbing attacks in recent weeks took place near subway stations, Kim said.