Six lights circle in the Salton Sea, California, area with no sound

We were at the Salton Sea on our way to Mexico.  We saw what we thought were lights on a series of radio towers.  They stayed in place for several minutes and then began to move in unison.  They silently flew in a giant circle from southwest to north east and then back to their original position.  They then went out.  The whole time taken was about a quarter hour, more or less.  There were somewhere between five and seven lights.
I did not report them because I thought people would think I was nuts.  Then, I saw a program on the Phoenix lights and they were similar to what my wife and I had seen.  There was no sound.
Witness indicates that date of incident is approximate.  PD