7 Marines Dead in Ariz. Helicopter Collision Occurred during a training exercise last night By Kate Seamons, Newser Staff Posted Feb 23, 2012 8:50 AM CST 5 comments Comments An AH-1W Cobra. (Getty Images) (Newser) – More tragedy for US troops today: Seven Marines are dead after two helicopters collided near Yuma, Arizona, last night. The Corps said the AH-1W Cobra and UH-1Y Huey were participating in a training exercise around 8pm when the accident occurred. The choppers were part of the 3rd Marine Aircraft Wing. The Arizona Republic reports that the accident is being investigated. The AP adds that teams reportedly train along the Arizona-California border because it mimics conditions in Afghanistan. The names of the dead won't be released for at least 24 hours.