Find them and charge them criminally with at least negligent homicide. They should then be punished by being bludgeoned to death by the cheap electronic equipment they were lusting for.
And yes, Walmart should be civilly liable. I like Walmart, but this stuff happens in some form or another seemingly every year. They need to realize that mobs are the worst form of humanity and that it wouldn't hurt to have an armed security personnel there who lets a few people in at a time in an orderly fashion when people are chanting "Break down the door!" outside.
I also realize Christmas is a completely secular holiday now, but these sorts of happenings during the Christmas shopping (ugh) season couldn't be a greater indictment of humanity or the reflection of our fallen state.