United States' Central Command said Thursday that a U.S. refueling plane has gone down in Iraq and rescue operations are underway.

The cause of the crash was not immediately clear but CENTCOM said it was not because of hostile fire or friendly fire. 

"The incident occurred in friendly airspace during Operation Epic Fury, and rescue efforts are ongoing," CENTCOM said. "Two aircraft were involved in the incident. One of the aircraft went down in western Iraq, and the second landed safely."

The refueling plane was part of the U.S.'s operations against Iran.