South Korea mistakenly fired an artillery shell toward the southern side of the Demilitarized Zone (DMZ) on Sunday afternoon and soon sent a message to North Korea that the firing was accidental, military officials said.

   No casualties occurred from the accidental discharge that took place at around 3 p.m., the officials said.

   An army artillery unit in the border town of Paju, Gyeonggi Province, mistakenly fired a 155mm towed howitzer while on training, they said. The shell landed some 14 kilometers north of the army base, on a hill on the South Korean side of the DMZ, they said.

   "The army unit was not engaging in an artillery firing exercise. A shell that had been loaded previously was mistakenly fired," an army official said.

   The military authorities sent a message to North Korea explaining that the firing was unintentional. North Korea has given no response, they said.

   Military authorities were investigating the incident, the officials said.

   Tensions are running high between the two Koreas after the North launched an artillery attack on a South Korean border island Tuesday, killing two marines and two civilians. The attack marked the first time since the 1950-53 Korean War that the communist neighbor targeted a civilian area. (Yonhap News)