All personnel aboard the U.S. HH-60 Pave Hawk that crashed Thursday evening in western Iraq were killed, U.S. Central Command said in a statement early Friday morning.

Defense officials said Thursday that seven troops were on board. All of those killed were American, another official told Military Times on background. He declined to provide any more information until the service members’ families have been notified.

The crash does not appear to have resulted from enemy fire. The incident is under investigation, according to officials.

"All personnel aboard were killed in the crash," said Brig. Gen. Jonathan Braga, director of operations for Combined Joint Task Force-Operation Inherent Resolve. "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."

The incident was immediately reported by another U.S. helicopter flying with the one that crashed, and a quick-reaction force comprised of Iraqi Security Forces and coalition members was dispatched to secure the scene.

"We are grateful to the Iraqi Security Forces for their immediate assistance in response to this tragic incident," Braga said. "Iraqi Security Forces continue to demonstrate their professionalism, capabilities and flexibility as we continue the fight towards a lasting defeat of Daesh."

Previously, a defense official confirmed to Military Times that the crash had occurred in Anbar Province, Iraq, near the town of al Qa’im. A strike report released by Operation Inherent Resolve Friday morning notes that a strike occurred in al Qa’im Thursday against an enemy supply route, indicating ISIS presence in the region.

However, the Pave Hawk, which is used by the Air Force for combat search and rescue, was not under fire and was on a routine route to move the helicopter from one location to another, the official said.

President Trump and Vice President Pence were among those expressing their condolences Friday morning.

Officials said that names of the fallen will be released by the Department of Defense only after their families have been notified.