PYONGYANG, North Korea >> A North Korean naval vessel sank last month, killing an unspecified number of officers and sailors, according to North and South Korean media.

The North’s official Korean Central News Agency provided few concrete details, and there was no clue as to what might have happened. KCNA said in a dispatch Saturday that the deaths came while a submarine chaser was performing “combat duties.”

North Korea rarely releases details about military mishaps or accidents.

The rest of the dispatch was devoted to a recent visit by leader Kim Jong Un to a “cemetery of fallen fighters.” He was shown in state media inspecting a large number of stone markers that carried photos of sailors.

KCNA’s dispatch said the incident happened in October, but did not give a date. Photos of the stone markers released by state media show “Oct. 13” inscribed on them.

An unidentified South Korean military source told the South’s Chosun Ilbo newspaper that the vessel was built in the 1960s, and that its old age might have been a factor in the sinking. The South’s Yonhap news agency, citing an unidentified source, reported that the vessel sank near Wonsan on the east coast.

Much of North Korea’s military equipment is decrepit, but the country has a massive army and thousands of artillery pieces deployed along its border.

The rival Koreas both claim the waters around their western sea boundary, which is the most likely scene of any future clash between them. North Korea disputes the boundary, which was unilaterally drawn close to its shores by the U.S.-led U.N. Command after the 1950-53 Korean War, and the two Koreas have fought several bloody naval skirmishes there since 1999.

Pyongyang is also blamed for a 2010 torpedo attack that sank a South Korean warship, killing 46 sailors. A North Korean artillery attack that year killed four South Koreans on a frontline island.

The Korean Peninsula officially remains in a state of war because the Korean War ended with an armistice, not a peace treaty.