My brother was telling me that he was awoken at night by a very loud bang noise. He looked out of the window and didn't see anything, but he didn't go back to bed for whatever reason. A short time later, he heard it again and looked out again to also see a flash of light. Then he saw some kids run away from a nearby alley and he realized what had happened: they had set off fireworks in the alley, which greatly amplified the bang.
After he told me this, we wondered if anyone else had heard it and what they thought of it, since it was so loud. Did people think it was gunshots or an explosion or something? So we did a web search for the local newspapers and sure enough, people had written in and there was an online article about it! About... the UFO sightings with loud noise and flashing lights that night.. :-/
Some people, when they don't know the cause of something, let their imaginations take over and believe the most far fetched garbage. No wonder there's so many conspiracy believers out there these days!