Horizontal Line of 7-9 Identially-Sized, Evenly Spaced, "Signalling" Lights.

2018/02/01, 18:35.
31°48.23265' N 111°2.66742' W – Green Valley, AZ.
Driving up Calle Tres, almost to Via Montana Vista, 7-9 identically-sized white lights, evenly spaced in a straight horizontal line, directly ahead of me, low in the sky.
Notes:  *The lights alternated on/off in what looked like signaling, then all turned off.  I don't know if every single light turned on/off, or in what order they did so.
*I'm not good at estimating size or distance, and it was dark, but my impression was that it was airliner size, maybe a 727's wingspan.  My first reaction was that it WAS an airliner, but that it was far too close to the ground.  Because I couldn’t see the mesquite ahead of me, I can’t guess how high up it was – it just felt “really close” to the ground for something so large.
*I was driving home from work.  It was after sunset - 18:35 - and the sky was dark to the west.
*I observed the UFO for approximately 1 minute, driving up Calle Tres.  As I stopped at the T intersection, the UFO had disappeared (lights all off).  It did not reappear, that I could see, after I'd turned south/left, although it now would have been on the passenger side of my car, so would have been difficult/impossible to see if it did.
*The area over which the UFO was is State Land - no buildings of any sort.  There are recreation vehicle trails through this, but I don't believe there is land at the elevation at which I observed the UFO (upon which ATVs could have been gathered).  And, would ATVs be able to turn headlights on/off independently?  I did, definitely, see that lights next to each other were independent of each other in turning on/off.  I did not hear any ATV sounds.
*Sierrita Mountains are west, and just north, of my location.  There is a lot of mining going on there, and a mining equipment sales area which shoots off fireworks when they make a sale.  This was not fireworks of any type I have ever seen: fireworks don't go on/off at each spot of light, nor are the spots identical and evenly spaced.  The known fireworks are shot off quite a distance from my location, but I can hear the reports; there was no sound.
*There is a lot of activity from Davis-Monthan AFB over my area, and a lot of BP plane & helicopter activity, as well.  I'm used to these, but there was no mechanical noise of any sort.  There was no discernable movement, either - the line of lights was stationary the entire (albeit short) time I observed it.
*I was playing music in the car, so might have missed fireworks reports, but would have heard an airplane/helicopter.
*Coincidentally, a few nights later, I watched the Smithsonian documentary about the solar plane's flight around the world - there was a definite similarity to the night shots of that craft landing - the long row of lights.  However, on the UFO, there were no other lights typical of known aircraft - no smaller red or green wing/tail lights, no rhythmic blinking of the white lights.  And, again, a known aircraft would make noise, would not turn off all lights at once, would have exploded if it hit the ground.
*I had an impression of a V shape, but that could've been subjective interpretation, since I couldn’t see any body shape, only the lights.
*I don't know much about drones - are they quiet?  And, if drones, why would they all turn their lights off at once?  It would have to have been multiple drones, or one huge single drone.
 Observer:  61-year-old female.  Have never before seen a UFO.  Have lived in same location for 19 years.  Educated, intelligent, logic-based.