SAN DIEGO (AP) - Last night's collision of two Marine helicopters over the California desert is under investigation.
    
The crash left seven Marines dead. Six were from Camp Pendleton in California, and one was based in Yuma, Arizona.
    
The accident involved an AH-1W "Cobra" that carries two crew members and a UH-1 "Huey" helicopter.

They collided in a remote portion of the Yuma Training Range Complex.
    
The U.S. military and its allies train in the hot, desert area ringed by mountains because the conditions are similar to Iraq and Afghanistan.