IRAQ – A US Air Force KC-135 refueling aircraft crashed in western Iraq during Operation Epic Fury on Thursday, killing all 6 crew members onboard.

Another tanker involved in the incident landed safely, according to US army.

The US Central Command (CENTCOM), which oversees military operations in the Mideast and parts of Asia, said a refueling aircraft was lost over Iraq during its operation against Iran, which began last month.

“U.S. Central Command is aware of the loss of a U.S. KC-135 refueling aircraft. The incident occurred in friendly airspace during Operation Epic Fury, and rescue efforts are ongoing,” it said in a statement.

Two aircraft were involved in the incident, CENTCOM said, adding that one of the aircraft went down in western Iraq, and the second landed “safely.”

“This was not due to hostile fire or friendly fire,” it said.

Iranian state TV, citing a spokesman for the Khatam al-Anbiya military headquarters affiliated with the elite Islamic Revolutionary Guard Corps, said the aircraft was struck by missiles fired by “resistance factions,” causing it to crash.

The spokesman said the aircraft belonged to the US military and that all the crew members were killed, according to the report.

A US official told CNN that at least five crew members were aboard the tanker that crashed. CENTCOM did not specify whether any personnel were injured or killed.

The crash took place in western Iraq, a sparsely populated desert region.

The military said further details would be released as the situation develops and asked for patience while additional information is gathered to provide clarity for the families of service members.

The KC-135 Stratotanker is used by the US Air Force primarily for aerial refueling operations. A typical flight crew includes a pilot, copilot, and boom operator responsible for mid-air refueling, though some missions may also include navigators.

The KC-135 fleet is among the oldest aircraft platforms still in service with the US Air Force. Based on the Boeing 707 passenger jet design, the last unit was delivered in 1965. Despite their age, the aircraft have undergone multiple upgrades, including engine replacements.

The aircraft can also be configured to transport cargo or medical patients.

The Air Force did not disclose the specific mission being carried out by the aircraft involved in Thursday’s incident.

The incident marks the fourth known aircraft loss since the Feb. 28 start of the conflict with Iran.

Last week, three F-15E Strike Eagle fighter jets were shot down over Kuwait in a mistaken friendly-fire incident, though all six crew members ejected safely.

Since Israel and the US launched joint attacks on Iran on Feb. 28, killing some 1,300 people, including then-Supreme Leader Ayatollah Ali Khamenei, hostilities have escalated.

Iran has retaliated with drone and missile strikes targeting Israel, Jordan, Iraq, and Gulf countries hosting US military assets.