A US Air Force KC-135 Stratotanker, a refueling aircraft, crashed in western Iraq on Thursday, the US military said, adding the incident was “not due to hostile fire or friendly fire” but involved a second US tanker.

The United States has deployed a large number of aircraft into the Middle East to take part in operations against Iran, Reuters reported.

In a statement, U.S. Central Command said it was carrying out rescue efforts after the U.S. KC-135 refueling aircraft went down. The ⁠second aircraft landed safely.

It did not specify whether any US service members had been hurt or killed.

“The incident occurred in friendly airspace during Operation Epic Fury,” the statement said, using the military name of the U.S. operation against Iran.

A U.S. official, speaking on the condition of anonymity, told Reuters the other aircraft involved in the incident was also a KC-135 and the one that crashed had as many as six service members on board.

According to Reuters, the Islamic Resistance in Iraq, an umbrella group of Iran-backed armed factions, claimed responsibility for downing the U.S. military refueling aircraft.

The group said in a statement it had shot ‌down ⁠the KC-135 aircraft “in defense of our country’s sovereignty and airspace”.

Since the U.S. and ⁠Israel started carrying out strikes against Iran on February 28, seven U.S. troops have been killed

Reuters reported on Tuesday that ⁠as many as 150 U.S. troops have been wounded in the U.S.-Israeli war on Iran. News of the crash comes the same day two U.S. sailors were injured after ⁠the USS Gerald Ford suffered a non-combat-related fire on board.