Both the Democratic People's Republic of Korea (DPRK) and the Republic of Korea (ROK) violated the armistice agreement that governs their shared border when their troops exchanged gunfire on May 3, the U.S.-led United Nations Command (UNC) said on Tuesday.

A multinational UNC special investigation team concluded that troops from both sides had violated the agreement, which has been in place since the 1950-1953 Korean War ended with an armistice rather than a peace treaty. 

The UNC, which is commanded by an American general, oversees affairs in the heavily fortified Demilitarized Zone (DMZ) between the DPRK and the ROK.

DPRK troops in a guard post committed a violation when they fired four rounds of 14.5mm ammunition at a UNC guard post on the southern side of the Military Demarcation Line (MDL) that divides the DMZ, the UNC said in a statement. No casualties or damages were reported in the incident.

ROK and U.S. officials have said they believe the gunshots were an accident, but the UNC said "the investigation was unable to definitively determine if the four rounds were fired intentionally or by mistake."

Read more:

Pompeo: Sunday gunfire exchange at Korean DMZ likely 'accidental'

DPRK calls ROK military drills 'grave provocation'

DRPK military officials acknowledged the receipt of questions from the investigators, but have not provided an official response, the UNC statement said.