During a fireworks display at Delco park on July 4th at 10:000pm my sister pointed out to me a strange object hovering in the sky directly to ourright. We had been sitting outside of the fence and facing the display. The object was seemingly a flat disc in the sky that looked abut the size of an airplane. The object was giving off a bluish purple light with a red dot of light in the center. It was completely stationary for about five minutes before slowly descending behind a tree. It came back up a few minutes later and moved up and down slowly for the rest of the display. As soon as the fireworks ended, the object turned red and slowly decended again. As we walked down the street, a large fireball, about the size of an aspirin, ascended in the sky. Soon after I noticed two more. together they created a triangle pattern across the sky. The fireballs continued their slow path upwards until they shot upwards into the sky at the same time at incredible speed, disappearing from sight. My family pointed out the aircraft to onlookers who were equally astonished. No fireworks seemed to cause these events.