An unidentified person entered North Korea after crossing the heavily guarded Demilitarized Zone (DMZ) with the South, military officials in Seoul said on Sunday.
South Korea's military said the person was seen walking through the 4-kilometer-wide DMZ that separates the two countries on Saturday night.
North Korea was notified of the border incident through a military communication line, Seoul said.
South Korean authorities later reviewed security footage and saw that the person broke through the barbed-wire fence to enter the buffer zone at around 6:40 p.m. (9:40 a.m. GMT) on Saturday, Yonhap news agency reported citing an unnamed Joint Chiefs of Staff (JCS) official.
The review indicated that authorities only detected the breach nearly three hours after it happened. Troops were deployed to capture the person but failed to do so, the JCS said.
It wasn't clear whether the person was a South Korean citizen or a North Korean.
It is extremely rare for South Koreans to cross into the North.
Before the coronavirus pandemic, some hundreds of people used to flee North Korea for various reasons, including political oppression and hunger, most of them settling in neighboring China.
