(CNN) -- South Korean military officials say investigators found eight land mines made by North Korea near the border between the two countries, state media reported Saturday.
A fisherman on Jumun Island alerted authorities after stumbling upon a landmine in a wooden box, the state-run Yonhap news agency reported, citing a spokesman for South Korea's Joint Chiefs of Staff.
Searchers found seven other mines on Jumum and two other islands in the Yellow Sea, as well as three empty wooden boxes, Yonhap said.
It was unclear how the land mines were identified. According to Yonhap, military officials said the mines may have drifted away from North Korea.
Jumun Island is just below the sea border between the two countries, Yonhap said.