The Organization for Security and Cooperation in Europe (OSCE) has identified an American paramedic who was killed by a land mine explosion in eastern Ukraine on April 23 while working as an OSCE monitor.
An OSCE statement on April 24 said U.S. citizen Joseph Stone was killed when an OSCE vehicle he was riding in hit a land mine in the separatist-controlled village of Pryshyb in the Luhansk region.
The statement said two other OSCE monitors injured by the blast -- a German woman and a man from the Czech Republic -- were released from a Luhansk hospital on April 24 and transferred to Kyiv.
It said the two were listed in stable condition.
Meanwhile, the armored Toyota B6 Land Cruiser that struck the land mine has been transported to Kramatorsk -- the Ukrainian government's provisional administrative center in the Donetsk region -- for what the OSCE described as an "ongoing assessment."
Ukraine's government in Kyiv and Russia-backed separatists in eastern Ukraine have blamed each other for the land mine explosion.
Self-proclaimed separatist leaders in the breakaway Luhansk region on April 24 claimed that Ukrainian "saboteurs" infiltrated territory under separatist control and planted the land mine in order to "discredit" the Russia-backed militants.
But Ukraine's Defense Ministry rejected that claim, noting that the site of the land mine has been under separatist control since the summer of 2014.
"There can be no Ukrainian sabotage groups, and are none" in this area, Ukraine's Defense Ministry spokesman Oleksandr Motuzyanyk said.
The U.S. State Department has said it was "shocked" about Stone's death while he serving as an international monitor in separatist-controlled territory of eastern Ukraine.
It called on Russia to use its influence with the separatists to allow the OSCE to conduct a "full, transparent, and timely investigation."
"This death underscores the increasingly dangerous conditions under which these courageous monitors work, including access restrictions, threats, and harassment," a State Department statement late on April 23 said.
Stone's death was the first among OSCE monitors, who were initially deployed to the region in 2014 to monitor cease-fires in a conflict that has killed at least 9,940 people.
EU foreign affairs chief Federica Mogherini said the incident was a "reminder of the urgent need for progress on a peaceful resolution of the conflict."
Austrian Foreign Minister Sebastian Kurz, who holds the rotating chairmanship of the OSCE in Europe, said there was a need for a "thorough investigation' and that "those responsible will be held accountable."
German Chancellor Angela Merkel made a similar call.
"The federal government expects that the parties to the conflict immediately do everything possible to ascertain how we reached this tragic point and who holds responsibility for it," she said.
Merkel also said it was time for all sides to start honoring a long-promised cease-fire, adding that the Russian-backed separatists bear the greater responsibility to make sure that happens.
German Foreign Minister Sigmar Gabriel lamented that "someone who just wanted to help create peace and put an end to the fighting has lost his life."
Ukrainian President Petro Poroshenko instructed Foreign Minister Pavlo Klimkin to keep the OSCE informed of Kyiv's investigation into the blast.
"This crime must be investigated and those responsible must be punished," Poroshenko wrote on Facebook.
"Ukraine condemns all forms of constant resistance by the rebels to the OSCE SMM's work," he added, using an acronym for the OSCE's special monitoring mission in eastern Ukraine.
Separatists Make 'Unsafe Route' Claim
A statement issued by the Russia-backed separatists in Luhansk on their website claimed that the OSCE team had veered off the main road and was traveling along an unsafe route.
"We know that this patrol team deviated from the main route and was moving along secondary roads, which is prohibited by the OSCE Special Monitoring Mission mandate," the separatist statement said.
Eduard Basurin, a senior separatist figure, said the OSCE vehicle "deviated from its main route and moved onto backroads" when it struck what he said was an antitank mine.
The separatists' claim could not be confirmed.
The unarmed, civilian OSCE mission, with more than 700 international observers, seeks to reduce tensions and report on the situation on the ground in Ukraine.
In March, the 57 member states of the OSCE, which include Ukraine, Russia, and the United States, decided by consensus to extend the mandate of the mission for another year, its third extension since it was first deployed in Ukraine in 2014.
Western nations have imposed sanctions on Moscow for its illegal annexation of Ukraine's Crimea Peninsula and its support for the separatists in eastern Ukraine.