A triangle shaped object moved over South Quincy into East Braintree.I was sitting outside facing West when a triangle shaped object about the size of a commercial airliner approached from the North, heading South. The object was flying at a much lower altitude than any aircraft of that size normally would. The object was making a sound that sounded like a fan buffeting air. The noise was loud enough to be clearly heard, and grew louder as the object approached. The object was shaped like a triangle, with a red light on the front tip and one white light on each back tip.When the object was directly in front of me it turned East, moving straight towards me as it lowered its altitude and its speed. When it was less than a football field away from me it suddenly turned Southeast, quickly accelerating its speed and moving out of my field of vision. Several black helicopters were seen in the area for the remainder of the night and the following day.