AH-1W "Cobra" helicopter [File photo]
Seven U.S. Marines were killed when two helicopters collided during a training exercise near Yuma, Arizona, the U.S. Marine Corps said Thursday.
The aircraft, an AH-1W "Cobra" and an UH-1Y "Huey," were conducting routine training operations when they collided Wednesday night, the U.S. Marine Corps said in a statement.
"The circumstances are being investigated," it said.
There were no survivors in the accident and the names of the victims were not released, CNN reported.
The Marines were from the 3rd Marine Airwing based at Miramar in Southern California.
The accident happened just five months after another major helicopter crash involving Marine Corps training.
A helicopter crashed during a training exercise at Southern California's Camp Pendleton in September, killing two Marines and setting off a 120-acre brush fire.