triangular craft moving just above the tree tops and telephone lines. Seen but different witnesses a block apart at the same time.

I was 14 walking to my house with a friend of mine. At the same time we both saw a triangular craft slowly moving just above the top of the trees and telephone lines. It continued up the street without a sound and we chased after it on foot but couldnt keep up with it. A block away my mother was in our drive way as she just arived home from shoping. She was pointing up in the air shouting for my father but when he came outside it was gone. She had seen the same thing as we did and to this day all three of us belive the object was "not man made" It was a perfect triangle with three equal sides,black and about 15 feet on each side and maybe 6 feet thick at the center but thinner at the edges. This sighting was 30 years ago but it made a lasting impression on all of us.
Date is approximate.  PD