Incheon Seobu Police Station on Tuesday said it is investigating a high school student on suspicion of threatening to kill elementary school students, which he claimed was a joke.

The suspect, whose exact identity was withheld by authorities, is believed to have posted that he would "kill all the kids while they are on their way home from school" around 9:35 a.m. Monday, via a KakaoTalk instant message board shared by parents of children who attend an elementary school in Seo-gu, Incheon. Also posted with the threat was a picture of a person holding the steering wheel of a car.

As uproar and safety concerns from parents ensued, police dispatched patrol cars and a strike team near the elementary school in question, as well as near a middle school and high school adjacent to it. School officials issued a warning to students and suspended after-school activities.

Police tracked down the suspect at around 8:15 p.m. later in the day. The suspect said it was just a joke, and that he did not intend to actually harm children.

Officials said they are mulling whether to press charges of obstruction of performance of official duties by force, punishable by up to five years in prison or a fine of 10 million won ($7,600). They also are considering a charge of preparation or conspiring of murder, under Article 255 of the Criminal Act, which is punishable by up to 10 years in prison.