US Military Aircraft Crashes in West Iraq, Killing 7

An RQ-11 Raven Small Unmanned Aircraft System is seen during the joint Israeli-US military "Juniper Cobra" exercise at the Tze'elim Urban Warfare Training Centre (UWTC) base in southern Israel on Mar. 12, 2018. Exercise Juniper Cobra is a five-day combined military exercise between Israel and the United States. (JACK GUEZ / AFP)

Several U.S. troops on a military helicopter that crashed in Iraq Thursday are believed to have been killed.

A Pentagon spokesman traveling with Defense Secretary Jim Mattis said all seven aboard died in the crash, NPR reported Friday.

Other officials indicated only that there are deaths.

The HH-60 Pave Hawk helicopter -- a variant of the Black Hawk -- crashed after hitting a power line in western Anbar province. It was not believed to have been shot down.

NPR reported that officials believe a mechanical fault may have played a role in the crash.

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"Rescue teams are responding to the scene of the downed aircraft at this time," a spokesperson for Operation Inherent Resolve said in an email to UPI. "An investigation will be initiated to determine the cause of the incident."

Iraqi security forces are assisting U.S. officials in the investigation, CBS News reported Friday.

The crash could be the first deadly chopper accident in Iraq since the United States began fighting Islamic State militants there in 2014.

The Department of Defense did not immediately confirm injuries or deaths.