A man who went on a deadly stabbing rampage that killed one person and injured three in Seoul said Sunday he committed the crime because "life was hard."

"I committed the crime because life was hard for me," he said on his way to the Seoul Central District Court.

"I was in a bad situation for a long period of time. I did extremely wrong things. I am a useless human being. I'm sorry."

Later in the afternoon, the court said in a statement that it issued an arrest warrant for the 33-year-old suspect surnamed Cho, as he poses a flight risk. The police are seeking charges of murder and attempted murder.

Cho was caught red-handed with a 30-centimeter knife at around 2:20 p.m. Friday. He had stabbed four passersby in an alleyway packed with mom-and-pop stores and eateries near Sillim Station on Seoul Metro's Line No. 2 in Gwanak-gu in southern Seoul.

One of the four victims -- a man in his 20s -- died and the three other men were sent to hospital for medical treatment. The victims did not know Cho, according to police.

Cho reportedly said during the police interrogation that he was "full of rage" because of personal circumstances and wanted to "make other people unhappy" too. Cho was also aware that the alleyway was bustling with people.

Cho tested negative in the initial drug test, according to results of samples sent to the National Forensic Service. Cho has been inconsistent over whether he was under the influence of any illegal drug, during the police interrogation.

Cho was found to have records of three convictions and more than a dozen juvenile crimes, according to police.

On Saturday, Justice Minister Han Dong-hoon said he would ramp up state supervision of high-risk individuals, as he was visiting the crime scene.

"It is the government's responsibility to take preemptive measures to deal with crimes by 'psychopaths' that are hard to prevent," he said.

"More research and preparations will be underway to practically prevent such crimes. I feel the need to come up with practical countermeasures," he said.

Police has yet to release test results on whether Cho could be considered a psychopath.

The knife rampage is a rare incident in Korea, where the number of intentional homicide victims remained below 1 for ever 100,000 people from 2011 to 2018 -- lower than the world's average of 5.8 out of 100,000, according to an estimate by the United Nations Office on Drugs and Crime.

Footage at the scene, including a video of the suspect wielding the knife and another where the suspect is being caught by the police, have gone viral on social media. Some have also disclosed what is believed to be the suspect's personal information online.

Police have asked the Korea Communications Standards Commission to remove such explicit footage and block the ordinary users' access to them to to curb the spread of such information on the internet. An act of revealing someone's identity in relation to a suspected crime is considered a criminal breach of personal information protection law in Korea, and violators may face up to three years of imprisonment or a 30 million won ($23,270) fine.