With practice they can fire really fast. Alternatively, just fire once, then disappear. Hard to tell where the shot came from.
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It's an interesting theory. But it sounds like this guy was shooting arrows in a populated area, even if in a small town. So he lets one go around a bunch of people in/around a store, then slips away after dropping the bow (leaving behind evidence)?
The guy was crazy enough to start shooting people with arrows, so I guess that highly risky scenario is possible.
There is a guy on a Youtube video that can rapid fire very rapidly and accurately while running or even hanging upside down. I wouldn’t want to try and charge him.