Tom Clancy handled this situation in his novel "The Teeth of the Tiger".
That was the only good part of that entire god forsakken novel... oh the depths to which Mr. Clancy has fallen....
I have already told my wife what to do in this event. Every mall I know of that we go to has a service hallway leading to the outside connected to the back of each store. That is where we are going ASAP. 95% of the "herd will head either towards the action/noise (stupid but true as behavioural scientists ahve noticed studying terrorist attacks in Isreal) or away. In either case that means a flood of people going both directions in a hallway packed with panicked people. Not the place to be. The service halls though lead out to loading bays and the like. The majority of people in those will be employees who have the sense to run, although history has shown many people will stand around trying to figure out what is going on. No matter what we want to be where the FEWEST people (targets) are. As soon as we are in the hallway I will then lead the way out. My logic is any terrorist in the main mallways will be far more focused on killing the masses than to bother with the 5% running down a service way so once we are on the way our rear is not my main concern. I would want to confirm any loading docks/exits are clear though before sending the wife and child through to safety.