Witnessed a blimplike craft moving slowly, no sound, wide circling lights speeding off and out of sight within 5 seconds

My friend and I were playing in the parking lot of our apartment complex. It was dark and we saw a slow moving, low altitude blimplike craft.  There was no sound. We initially thought it was a blimp, but as low as it was flying, we should have heard the motor.  
It moved to the rear of my apartment building and we ran into my apartment which had a balcony.  
My Parents and Brother were in the apartment and joined us on the balcony.  We saw it again moving slowly from left to right at about the speed of a blimp.  
It had lights which appeared to circle the craft.  They were about the size of lights on a blimp but were not letters.  Letters would have been easily read as low as it was positioned.  
What really convinced us that it wasn't a blimp was that after about 30 seconds of moving after we got to the balcony, it suddenly took off directly away from us and was out of sight within 5 seconds.  Again, making no noise whatsoever. 
I am 48 years of age and am open to the possibility that ufo's exist, but have not experienced another sighting since that night.
Date is approximate.  PD