KIEV, April 24 - A member of the European monitoring mission in eastern Ukraine was killed and two others were injured Sunday when their vehicle drove over a mine near Luhansk, Reuters reported.

The Organization for Security and Cooperation in Europe, which runs the monitoring mission, said it was investigating.

The monitor who was killed was an American man, according to a spokesman for the Foreign Ministry of Austria, which holds the rotating presidency of the 57-nation organization. The man’s name was not released.

The mission has had more than 700 unarmed civilian monitors deployed in eastern Ukraine since 2014. Their role now is to keep track of whether government forces and Russian-backed separatists in the region are complying with a 2015 cease-fire agreement, including commitments to withdraw heavy weapons.

The organization confirmed that the episode involved a patrol of six monitors in two armored vehicles.

The Austrian Foreign Ministry said one of the two people injured was a German woman. Alexander Hug, the principal deputy chief of the monitoring mission, told reporters that the other person injured was from the Czech Republic. No other details about the person were immediately available.

Hug noted that all sides in the simmering conflict in eastern Ukraine had made binding commitments to remove all of their mines and other explosive devices. “Sadly, particularly for our mission today, and for all civilians in the area, the commitments remain true only on paper,” he said.

Tensions remain high in the region, where most people speak Russian rather than Ukrainian and armed militias seized government buildings and unilaterally declared independence after the annexation of Ukraine’s Crimea region by Russia in 2014. The 2015 cease-fire is violated regularly. (rt/ez)