Ufologists tricked the residents of the German city of Heilbronn into thinking they were under attack from "flying saucers". The UFOs were visible for 15 minutes.
Made of kite paper, the UFOs were balloons measuring 1.5 by 1.8m. Due to the material they exuded an "unearthly, orangey-red glow", said Werner Walter, head of national research network on extraordinary celestial phenomena.
Walter said: "It was like a Hollywood film. People were running outside, calling one another and discussing it in groups. There are things that we can't make sense of when we see them for the first time. But mostly there is a simple explanation..."