UFO Sighting in Phoenix Metro area in the vicinity of Sky Harbor International Airport

At approximately 10:15pm Arizona time, I was driving westbound on Curry Road in north Tempe, Arizona.  Curry road almost directy runs into Sky Harbor International Airport before curving around and becoming Washington Street which runs into Phoenix.  As I was driving, my girlfriend in the passenger seat said, "Hey what is that?" and pointed at 6 glowing lights that were orange/amber in color that looked like inbound aircraft.  Except instead of moving in for what looked like an approach to land, they simply hovered in a pattern. I couldn't determine if they were directly over the airport, due to the fact I was still several miles east of Sky Harbor, or if they were beyond the airport itself. I thought they might have been signal flares, since there is a large Air Force base in the west valley, but it seemed highly unusual that would happen.  They also did not behave like signal flares as they did not drop in altitutde and maintained their movements in! a pattern together.  As I turned left on Mill Avenue, now going southbound, my girlfriend and I both saw that their lights were disappearing.  It seemed like they were moving northwest and gaining in altitude before the light would disappear.  I crossed the Mill Avenue bridge and turned going westbound onto Rio Salado Parkway to try to keep a visual on them.  I stopped my car and pulled over just before Hardy Drive on the north side of Rio Salado Parkway and saw only one of them left.  From what I could tell it was some kind of aircraft, but it seemed to be traveling eastbound at a high rate of speed, before it would slow down to almost a hover, then would speed along some more.  Then it seemed to abruptly change directions and head northwest gaining altitude before the light completely disappeared from view.