SAN DIEGO -- San Diego-area Marines are awaiting news about the four Americans killed aboard a CH-46 helicopter that crashed in Kuwait Thursday.

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The big twin-rotor chopper known as a Sea Knight (pictured, right) went down near the Iraq border, killing all 12 soldiers aboard. Eight were British Marines.

The deaths were believed to be the first U.S. casualties in the war.

No hostile fire was reported in the area, and the crash may have been due to mechanical problems, according to 10News.

The 3rd Marine Aircraft Wing based at Marine Corps Air Station Miramar provides air transportation for the 1st Marine Expeditionary Force -- a 45,000-troop force that includes many Camp Pendleton-based Marines.

Deployments of Camp Pendleton-based Marines with the 1st Expeditionary Force began in mid-November.

Lt. Greg Scott, a spokesman for the Miramar-based aircraft wing, said he had no immediate information about the Americans killed, but said it was possible they were locally based.

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All but one of the six squadrons of CH-46s based at Miramar or Camp Pendleton has been deployed to the Persian Gulf. Each squadron includes about 10 helicopters.

Sea Knights have a crew of four, carry up to 40 combat troops and can fly day or night in any weather. The Boeing-made choppers, considered a workhorse for moving troops and supplies, has had a troubled history.

The Marines fleet of more than 200 CH-46s was grounded last year after an inspection revealed a possible mechanical defect.

Meanwhile, a Marine from the Camp Pendleton-based 1st Marine Expeditionary Force was killed in Iraq Friday, 10News reported.

The Marine felled by Iraqi gunfire marked the first U.S. combat loss in the war against Saddam Hussein.