Military helicopters collide in southeast California killing 7

Two military helicopters collided Wednesday night near a remote region in southeast California, killing seven Marines, the Marine Corps Air Station Yuma said in a statement.

The helicopters, an AH-1W “Cobra” and UH-1Y “Huey,” were conducting a routine training exercise at 8 p.m., the statement said. The helicopters were over southeast California in the Chocolate Mountain Aerial Gunnery Range, Dustin Dunk, the public affairs chief from the air station, said.

Maureen Dooley, a Miramar public affairs officer, told Fox News Radio that Marines use the training area because the terrain is similar to what they would face in Afghanistan. These training sessions help them gain some familiarity before they deploy.

"We do not know what caused it," Dooley said.  "That is what the investigation will reveal to us."

The Marines started an investigation into the incident, which can take months to complete.

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The identities of the Marines will be released after their families are informed about the incident.

Sen. John McCain, R-Ariz., said his thoughts and prayers are with the families of those killed in the crash.

"This tragedy is a grave reminder of the sacrifices the men and women of our armed forces make to keep us safe – both in training here at home and in combat abroad," he said in a statement.

Capt. Staci Reidinger, director of public affairs at Marine Corps Air Station Yuma said earlier Thursday that the crash happened west of the Chocolate Mountains in California, though the exact location hasn't been confirmed.

"It's not in a populated area," she said.

Several accidents have happened in the past year involving Marine Corps training in Southern California.

In September, a helicopter went down during a training exercise at Camp Pendleton, killed the two Marines onboard and set off a fast-moving brush fire at Camp Pendleton.

In August, two Marines were ejected from their F/A-18 Hornet fighter jet as it plunged toward the Pacific Ocean. The two Marines spent four hours in the dark, chilly ocean before they were rescued. Both survived.

In July, a decorated Marine from western New York was killed during a training exercise when his UH-1Y helicopter went down in a remote section of Camp Pendleton, north of San Diego.

Another Hornet sustained at least $1 million damage when its engine caught fire on March 30 aboard the USS John C. Stennis during a training exercise about 100 miles off the San Diego coast. Eight sailors, a Marine and two civilians were injured.

A decade ago, in February 2002, a helicopter crash in the Chocolate Mountains in eastern Imperial County, Calif., killed two Camp Pendleton Marines and injured two others. The UH-1N "Huey" was on a routine training mission in the Naval gunnery range.

The Associated Press contributed to this report.