Three South Korean military personnel were injured Monday in an “unidentified explosion” while operating inside the western sector of the Demilitarized Zone, according to the country’s military.

Two of the injured personnel were airlifted by emergency medical helicopter to the Korean Armed Forces Capital Hospital near Seoul, where they were receiving treatment, a Ministry of National Defense spokesman said in a text message to reporters that afternoon.

The third injured person and other personnel involved in the operation were also taken to the hospital for medical examinations, the spokesman said.

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