My son, age 39, and two friends, were outside talking, when my son saw what he said looked like a firefly moving from some trees across the ground to a nearby Lilac bush. Fireflies are quite rare in this region. He said that it then started to get brighter and he said 'walk with me,' to his 2 friends who were facing the opposite direction and had not seen the 'item'. The friends simply thought he wanted to talk more privately, away from other people gathered outside for a birthday party.When they came around to the side of the bush, it suddenly grew to the size of a baseball, while at the same time turning a bright blue. At this point the other 2 men saw the thing while it was still at the base of the bushes and were quite startled by it, and it suddenly zoomed across the open field, went over a parked abandoned school bus and into the sky in a Southwest direction. All with no sound.