People often claim they saw or heard something, but it turns out to be untrue. Some make these claims just to get their 15 minutes of fame. Others might think, for example, they heard what sounded like more than one person firing, but they instead might have heard echoes or bullets ricocheting. I often see interviews with law enforcement where they say eyewitness testimony can be unreliable. I think that may be true. Under stress, our brains are likely to misinterpret things in the wrong way or we see things that aren't there.