Weird Light Formation Over Chicago

Witness recorded weird flying objects in the Chicago. He was watching fireworks. Many planes flew by that night, as well, but these lights appeared to hover in the distance. Sometimes he saw one or two UFOs and he wasn't sure if he was seeing someone's drone, but at one point the lights seemed to be in formation. The lights would go away when people stopped shooting off fireworks for a few minutes, and then often seemed to reappear once people resumed the fireworks. Sometimes he saw the UFOs and the planes at the same time.