A U.S. Marine AH-1 Cobra helicopter crashed in an insurgent stronghold in western Iraq on Saturday, and two crew members were missing, the U.S. military said. Hostile fire was not suspected as the cause.

The helicopter was on a maintenance test flight when it went down, and search-and-rescue efforts were under way, the statement said.

"We are using all the resources available to find our missing comrades," Marine spokesman Lt. Col. Bryan Salas said.

The statement added that "the incident does not appear to be a result of enemy action."

The statement did not specify where exactly the helicopter crashed in Anbar, a huge, insurgent-infested province extending from the western outskirts of Baghdad to the Syrian and Jordanian borders.

CountryWatch: Iraq