Four U.S. service members are dead after a military refueling tanker crashed in western Iraq.

U.S. Central Command confirmed the deaths early Friday morning. The status of two other crew members is unknown but the military says rescue efforts continue.

The aircraft, a KC-135 Stratotanker taking part in Operation Epic Fury, went down around 2 p.m.Thursday. CENTCOM says the incident happened in friendly airspace and was not due to hostile or friendly fire.

The military says two aircraft were involved and the other landed safely.

Service members in a Kansas Air National Guard air refueling wing deployed in support of the U.S.-Israeli war with Iran earlier this month.  The 190th Air Refueling Wing is stationed at Forbes Field in Topeka, and is one of two refueling wings based in Kansas.