The variety of different reactions from the various spectators is fascinating. Some are hitting the ground while others don't react at all. It just brings home how sudden and shocking the event was. Something that is lost in all the pedantic analysis of every frame.
It's different in a war zone. Most would hit the ground at the first shot. A domestic situation is different, where violence is not expected. In DP, I would say most remained in their "comfort zone" for the first two shots. Many dismissed the first report as a "backfire" or "firecracker". There's no obvious gunman and there are urban structures that distort the sound waves. On hearing the third shot and (if they were in a suitable position) seeing the head shot, only then did a few hit the ground, including the Newmans. Some, like a man on the stairway on the knoll, and the Hesters tried to be less in the open. The Wiegman film shows hardly any panic in the crowd even after the head shot (could be they thought it was just firecrackers). If the siren came on just before the head shot, that could indicate to some the reality of what they were witnessing.
I don't know if its been discussed before, but I spotted a woman turning her head sharply rightward beginning in the Z160s; she's turned forward again by Z193. It could mean something as regards the first shot; it could mean nothing. That's one reason why the JFKA "controversy" drags on, with no end in sight. Things in the film (not exactly HD to begin with) can be interpreted in a variety of ways.
