A former Tucson paramedic died Sunday while working as a monitor of the crisis in Ukraine.

Joseph Stone, 36, worked for the Organization for Security and Cooperation in Europe, which identified him as the victim of an explosion that hit an armored vehicle in the Luhansk region of eastern Ukraine. Two other OSCE workers were hospitalized.

The OSCE monitoring mission is made up of unarmed civilians from various countries who observe and report on activity in Ukraine and help foster dialogue among the parties fighting each other.

Before working with aid groups in countries like Afghanistan, Liberia, and Ukraine, Stone grew up in Tucson, graduated from Pima Community College and worked for nine years as a paramedic, said his brother Matthew, 34.

“The world really did lose something special on April 23,” Matthew Stone said.

In recent years, Joseph worked near war zones, but Ukraine was the first time he had worked inside an active war zone, Stone said.

“He always downplayed the danger of it, but it was there,” Stone said.