59 DEAD  500+ wounded and a 350 yard shot is within 10 inches consistently for even a moderately good shooter without a scope. We qualified at 300 yards and a 3" bullseye.   I am not sure you understand how accurate the M-16 can be in the hands of a trained user.  One degree is a hemisphere away from a target.  No one could aim that bad.    And absolutely shoot at a occupied hotel.   The odds of hitting anyone is zero.  They weren't packed in like cattle as they were at the concert and any trained shooter could put a round within 10 inches of the rifle flash, which they could see.  Maybe you need to think your risk management.   Actually, the biggest risk would be someone like you who would kill the person firing back out of an abundance of caution.