Even training is dangerous.

via CNN.

(CNN) -- Two helicopters collided midair during a training exercise, killing seven Marines, the U.S. Marine Corps said Thursday.
Wednesday night's crash occurred during routine training operations at the Marine Corps air station near Yuma, Arizona, the Marine Corps said in a statement.
The aircraft, an AH-1W "Cobra" and a UH-1Y "Huey," were part of the 3rd Marine Aircraft Wing.
Authorities said they would not release the names of the Marines involved until their families were notified.
Marine Corps Air Station Yuma has about 4,000 active-duty Marines and sailors, and supports 80% of the Marine Corps air-to-ground aviation training. It covers five square miles in southeastern Yuma and is home to a number of units.
The air station "hosts approximately 70 aviation units, bringing an average of 600 aircraft and 14,000 personnel for ongoing training that takes place throughout the year," utilizing U.S. and NATO forces, the station's website said.

Terrible news.