The Department of War confirmed Friday all six crewmembers were killed when an Air Force refueling tanker crashed in Iraq.

United States Central Command (CENTCOM) acknowledged that the Boeing KC-135 Stratotanker, carrying six service members, went down over western Iraq while noting that a second aircraft landed safely, CENTCOM said in a statement released Friday. The incident is under investigation, while two more servicemembers, previously reported missing, were confirmed dead later in a second statement released later Friday morning.

“At approximately 2 pm ET on March 12, a U.S. KC-135 refueling aircraft went down in western Iraq,” CENTCOM said. “Four of six crew members on board the aircraft have been confirmed deceased as rescue efforts continue. The circumstances of the incident are under investigation. However, the loss of the aircraft was not due to hostile fire or friendly fire.”

“All six crew members aboard a U.S. KC-135 refueling aircraft that went down in western Iraq are now confirmed deceased,” CENTCOM said in the second release.

Six American servicemembers were killed in an Iranian attack on an operations center in Kuwait, a seventh died of wounds sustained in an Iranian attack on an American base in Saudi Arabia and another American servicemember died from a medical incident since President Donald Trump announced the start of Operation Epic Fury.

The Air Force lost three F-15E Strike Eagles in a friendly fire incident over Kuwait, with all six crew on the multi-role fighters ejecting safely.

The DoW did not respond to a request for comment from the Daily Caller News Foundation.

The KC-135 first entered service with the United States Air Force in 1956, according to an Air Force fact sheet. It is capable of refueling aircraft either by using a “boom” that plugs into the receiving aircraft or by using a “probe and drogue” system.

The Air Force had 414 KC-135s on inventory, according to the Air Force web site, with 167 on active duty. The ancient aerial refueling aircraft are being replaced by the Boeing KC-46 Pegasus tanker, which is based on the Boeing 767 airliner.

Normally, a KC-135 carries a crew of three (pilot, co-pilot, and boom operator). The Pentagon did not explain why there were extra crew members on board in their statement confirming the casualties.

Trump has faced heightened scrutiny over his decision to launch strikes against Iran, including a bomb that hit an elementary school and killed 175 people. The president has reiterated that the conflict would end “soon,” but has not given a definitive timeline.

Editor’s Note: This Article has been updated to reflect the two other occupants of the plane, initially presumed missing, were killed.