This initially threw me for a loop prior to looking into it a little.
There is a very low range of hills in the R-2510 just NW of El Centro, CA (near Yuma, AZ).
I figured it might a typical media inaccuracy in reporting details, but I see now that there is a range east of Phoenix and the Sheriff mentions taking off out of Falcon Field.

Sorry to hear about this mishap.

USMCFLYR