Low Flying Helicopter Chasing Lighted Object

Was in my home in South Tempe near Baseline and the 101 Freeway, when I heard the sounds of one or more large helicopters passing overhead.  I remained indoors, when about 5 minutes later the event was repeated.  
On the third occasion, I ran outside and observed a single helicopter with navigational lights on at a very low altitude (under 500 feet) passing from north to south.  It was tailing an object which appeared to be longitudinal and tapered of about the same length as the helicopter.  The object had a string of approximately 20-25 small white unvarying lights arranged along its length.  The object displayed no other lights.  
The helicopter appeared to be a Blackhawk, although that is just a guess as it was difficult to see due to darkness.
 Previously, we have in the past had Marine helicopters occasionally perform similar maneuvers in our area when practicing urban combat training.  However those occasions were marked by that was always announced well in advance and there was no such announcement on this occasion.