UFO Sighting in Denver, Colorado on 2017-07-04 21:35:00 - 4 teardrop objects moving in a circle

My wife and i were viewing fireworks over the denver metro area as i have done for over 40 years at this location. my wife and i saw 4 teardrop objects moving in what appeared to be an oval. the objects looked to be far to the east of denver thus 20 to 30 miles away. they appeared one by one until all 4 were visible. they seamed to turn and move in an oval path. at times one or two of them would disappear and then reappear. they were far above any of the fireworks we saw and did not appear to behave like any fireworks i have ever seen. that is why they caught my attention. i have view many aircraft at this location for over 40 years. they stayed at about the same level in the sky as they moved. after a couple of minutes they disappeared one at a time. i could not see any sign of smoke or exhaust near the objects. the four seemed to move in a loose formation as they went in an oval. i was looking east northeast from green mountain across denver. we are at 6000 feet so we can see across denver to slightly beyond dia airport. the objects looked to be somewhere between downtown denver and the horizon. these objects were much bigger than any aircraft that i have seen in that directions. airplanes and helicopter lights are much small than these objects. compared to aircraft that i have seen at that distance the objects moved faster. i wrote up my notes on the event right after the objects disappeared. the event ended so quickly i did not have a change to view it with binoculars or take a telephoto picture.