I came here to note that one thing that has come out since that day was that the entire incident took only 82 secs from start to finish. And most of the carnage occurred in the first 10-15 secs.
It illustrates how fast most of these incidents occur. I think this was one of quickest reactions by a LEO to use deadly force to eliminate a threat. After viewing some of the CC video and the photo feed, I am of the opinion that only the officer killed at the gate might have been saved with an earlier armed response but even that is a tossup as it appears the attacker was in the midst of others running from the scene.
But I also wanted to agree with OlJock99 about photos and context.
You are looking at 1/500 of a sec, so be very careful of making generalizations from that small slice of time.
I have photos I took at a horrific scene where minutes earlier 27 people had been killed that would make Dallas Cowboys fans look like complete a-holes without context. People in the midst of this sort of incident do strange things as the brain works to comprehend what is going on around them.
This is why radio producers need avoid doing the job of a photo editor. It would be like someone recording slices of their audio to make a radio show say something entirely different than what was said. It isn't very civil and the web now brings out the certifiable and those that are genuinely reprehensible (Like Richard Spencer, et al.)
See some of the tweets directed towards this woman, what the photographer said about the pics, and the woman's response (from a paper on the the conservative side of English media)
http://www.telegraph.co.uk/news/2017/03/24/muslim-woman-bridge-westminster-attack-speaks-becoming-target/Be better than this Ags.