The South Korea military fired warning shots at an unidentified object crossing the inter-Korean border from North Korea Tuesday afternoon.

South Korea’s Joint Chief of Staff said that the military detected the object flying across the Military Demarcation Line(MDL) southward in the Chorwon area in Gangwon Province at around 4 p.m.

The JCS added that the military fired about 90 rounds of K-3 machine gun as warning shots along with a warning broadcast.

The South’s military is looking into the incident, suspecting that the object could be a North Korean drone.