Lights and beems over AZ desert

As we were traveling south on Interstate 10 towards Tucson at approximately 1am, there was no one else on the interstate, naturally.  I happened to glance out my side window, thinking I had just seen a flash of lightning off in the distance.  But what I saw was far less mundane.  About 300 yds off the hiway was a light hovering about 300ft above the ground.  The odd thing about the light was its erratic behavior.  It seemed to be darting all over the place.  It would move, stop, and shoot a pinpoint beem of bright white light to the ground, that illuminated the ground like daylight.  Having just been to the Grand Canyon that day I had my camera in the truck with me.  So I reached for the camera, and having just been to the Grand Canyon, I had used all my film earlier that day, naturally.  My wife, her sister and myself watched this fo about 15 mins before it shot off and we went on to My sister-in-laws house in Tucson.
Date is approximate.  PD