Having worked in a bank and been there during an armed holdup, things seemed to go very slow and your thought processes certainly do slow. Staying still and discreetly observing are the usual direction you take so as to have a better chance of staying unharmed and giving Police a description of the perpetrator and the proceedings.
Even in that circumstance needed counselling in the following days as it is then that it hits you. Disbelief, relief, call it what you will but an overwhelming sense of having dodged harm.
The poor souls in the shopping centre were just going about a normal activity and would not have known what hit them.