'No survivors' in American helicopter crash in Iraq, says Washington

The aircraft crashed in western Iraq a day earlier, the officials said, insisting on speaking anonymously to release details of the crash before they were made public.

The crash did not appear to be the result of enemy activity and is under investigation, the Pentagon said.

"This tragedy reminds us of the risks our men and women face every day in service of our nations. We are thinking of the loved ones of these service members today," said US Army Brig. Gen. Jonathan P. Braga, director of operations in the fight against the Islamic State extremist group in Iraq and Syria.

The helicopter was used by the Air Force for combat search and rescue and was shifting from one location to another when it went down Thursday afternoon near the town of Qaim in Anbar Province.

The Pentagon said an accompanying US helicopter immediately reported the crash and a quick-reaction force comprised of Iraqi security forces and coalition members secured the scene. 

The names of those killed would be released after next of kin are notified, the statement added.

The US-led coalition battling the Islamic State group in Iraq and Syria have an outpost in Qaim, which is located near the Syrian border.

The anti-IS campaign accelerated through much of last year, as coalition and Iraqi forces battled to take back a string of cities and towns.

Iraqi Prime Minister Haider al-Abadi declared victory over IS in Mosul in July. In the following months, Iraqi forces retook a handful of other IS-held towns including Tal Afar in August, Hawija in September and Qaim in October. In November, Iraqi forces retook the last Iraqi town held by IS - Rawah, near the border with Syria.

The US-led coalition has continued to work with Iraq and Syrian Democratic Forces to shore up the border region to make sure that foreign fighters and insurgents can't move freely across the region.