KYIV -- RFE/RL has obtained a video via an official Ukrainian source that shows the moment a vehicle carrying OSCE monitors was struck by an explosion during a patrol in eastern Ukraine's conflict zone, killing an American and injuring a German and a Czech.

The clip captures a fireball and huge plume of black smoke as the second of two marked white cars traveling in separatist-controlled territory on April 23 struck what OSCE Secretary-General Lamberto Zannier said was "a mine...left on a road which is also used by civilians."

The victims were part of the Organization for Security and Cooperation in Europe’s Special Monitoring Mission (OSCE SMM), an unarmed, civilian operation with more than 650 representatives working to reduce tensions and report on the situation on the ground in Ukraine’s conflict zone.

The death of Joseph Stone, a 36-year-old paramedic, marked the OSCE mission's first death in a 3-year-old conflict that has killed more than 9,900 people as Ukrainian forces battle Russia-backed separatists.

The OSCE has opened an internal probe and Kyiv authorities have launched a criminal investigation into the incident.*

Ukrainian government officials have blamed separatists, who have in turn said Kyiv was responsible for Stone's death.

The six members of the OSCE team were traveling in two armored Land Cruisers near Pryshyb, in the Luhansk region, a town that sits right up against the front line of the conflict.

At an April 28 press conference, OSCE Deputy Chief Monitor Alexander Hug said the route where the vehicle struck the explosive, likely a mine, was a planned route on a secondary road used two hours earlier and the previous day by the monitoring team.

Hug said the blast was powerful enough to throw the 4 1/2-ton armored Toyota 7 meters away "and fully destroy it."



The video -- filmed from a northerly position and the only one of the incident to be unearthed thus far -- shows the two OSCE SMM vehicles driving east on a secondary road before disappearing behind a row of trees at 11:17 a.m. local time. Seconds later, after the camera is jarred or deliberately moved to follow the cars' route and as the camera focuses, a ball of flames and thick black smoke mushroom above the tree line.

WATCH: The Moment An OSCE Vehicle Exploded In Ukraine





In an extended version of the clip, a third, unidentified vehicle appears nine minutes later heading in the direction of the blast.

The source that provided the video to RFE/RL said the road has been used infrequently by civilians for some time due to its proximity to the front line and military activity around it.



The OSCE mission will release the findings of its own investigation into the incident once they are confirmed, Hug said.



The OSCE SMM has repeatedly demanded the removal of land mines and unexploded ordnance or, where that proves impossible, mapping, marking, and fencing off such areas.

In 2016, the OSCE mission verified 141 land mines and other explosives that caused civilian casualties in the region, including 96 injuries and 45 deaths of both adults and children.

* This story has been amended to clarify that Kyiv authorities, not the OSCE, have launched a criminal investigation into the incident.