Seven international peacekeepers, including five Americans, were killed Thursday when a U.S. Army Black Hawk helicopter crashed during a routine mission in Egypt’s Sinai Peninsula, writes VOA.

The Multinational Force and Observers, a group that monitors the 1979 Israeli-Egyptian peace accord and owned the aircraft, reported that the two additional victims were French and Czech. The MFO declined to release the names of the dead, pending the notification of their families.

An eighth crew member, also an American, was badly injured in the crash, and was subsequently airlifted to an Israeli hospital.

Both Israeli and Egyptian officials say the crash appears to have been an accident, and that there were no signs of the aircraft being attacked. The Czech Republic’s military attributed the Black Hawk crash to technical malfunctions.

In a press release, the MFO said the group will conduct a further investigation into the cause of the accident.