A man died and another was injured in an explosion in a restricted area in Yeoncheon near the border with North Korea, possibly from a wooden box land mine, police said Sunday.

The explosion occurred around 11:20 p.m. on Saturday in a border city 60 kilometers northeast of Seoul. A 48-year-old man, known only by his last name Han, died at the scene, while a 25-year-old man with the last name Kim was taken to a hospital with injuries.

Police said that the two were carrying what appears to be a boxed landmine that they picked up on their way back from fishing at the Imjin River. The area where they were fishing is off limits to civilians.

Police and military officials say that they are investigating the exact cause of the accident and how the men were able to gain entrance to the area.

It has yet to be confirmed whether the explosive drifted down waters from North Korea. On Saturday, military officials issued warnings to locals to take extra caution after authorities discovered eight wooden box landmines, which they said probably floated south from North Korea.

Meanwhile, military said Saturday that eight anti-personnel mines made by North Korea were discovered in western coastal areas near their heavily-armed border.

"The military and police jointly conducted a search at the tip of a fisherman who discovered a wooden box landmine on Jumun Island around 6:30 p.m. yesterday," an official for the Joint Chiefs of Staff said. The small island in the Yellow Sea is located just below the sea border between the two Koreas.

The searchers found seven other mines on Jumun and two nearby islands as well as three empty wooden boxes, the official added.

All eight of the mines were blown up by the military, which officials said may have drifted away from the North.