South Korean police said Wednesday that a man in his 40s has been arrested for threatening to murder Han Dong-hoon, the chairman of the emergency leadership committee of the ruling People Power Party.

The suspect wrote the online post at around 9:40 p.m. on Tuesday, vowing to attack the ruling party's interim leader during his visit to Gwangju, according to Gwangju Gwangsan Police Station. Han is slated to visit the southwestern city on Thursday.

The suspect was arrested without a warrant at around 5:20 a.m. Wednesday at his home in Gwangsan-gu district in the city. South Korea's Criminal Act states that investigators can arrest a suspect without a warrant when there is probable cause that he or she has committed a crime punishable by at least three years in prison.

Gwangju Metropolitan Police Agency had already said Tuesday that it would step up security for Han, in the wake of a knife attack on main opposition Democratic Party leader Lee Jae-myung that occurred earlier in the day. Lee was attacked in Busan by a 67-year-old man, who later told police he intended to kill the opposition leader.

Lee’s injuries were not life-threatening, and he is currently recovering after a surgery.