A militia loyal to eastern Ukrainian protesters has taken a busload of hostages today, including five Ukranian soldiers, a driver and seven monitors from the Organization for Security and Cooperation in Europe (OSCE).

The capture of the Ukrainian troops is unsurprising, as Ukraine’s Interior Ministry is openly talking up an invasion of the protesters’ cities to “liquidate” them, but the capture of the OSCE monitors took many by surprise.

The German-led OSCE monitors lost contact with their nation’s Defense Ministry earlier today, and are reportedly being held inside Slovyansk, along with the soldiers, at a former Ukrainian government security force building.

Slovyansk’s pro-protester mayor defended the capture, saying they had found “forbidden ammunition” on board the bus. He also claimed one of the soldiers was “an employee of Kiev’s secret military staff.”

Talks are ongoing to secure the release of the monitors, though Ukraine’s interim government claimed the protesters were refusing to release anyone until they have spoken to Russian officials.