I don't mean to be rude, but have you put much thought into this post?
I think it is fair to assume that the Police have all had similar training.
From what I have read, that training includes shooting twice (so called double tap) rather than once only. This is to ensure the threat is neutralised.
Given that the training would include threat recognition, isn't it also fair to assume that all three Officers that did shoot came to the same conclusion at roughly the same time? IE : This person is out of control and is about to harm the fourth Officer. Therefore they would have done the "double tap" at near enough to the same time.
The tone of your post seems to imply that they took turns shooting one at a time and a little thought indicates the fallacy of that.

