Ah. Nothing like a little chaos in your Christmas holiday, eh. But I keep seeing the gathering point being the "social media". Isn't that a misnomer at this point? it this be re-termed "anti-social media?" :-D
By observing the ensuing discussion in most comment sections under the relevant articles on the event, I'm left with the impression that this was all a staged event. Live feeds have been detected from various locations, the brawls happening almost simultaneously, and people alleging that some police stations even knew ahead of time what malls this was going to happen in.
The general impression is that this was organized through (anti?-)social media to start at roughly the same time (8pm Eastern), just before the malls closed. It mostly happened in the food courts - some starting with fireworks, others with different loud noises to create panic. By 10pm there were at least 20 malls involved, and we can see in some of the vids that the kids who started it are laughing as they're falling over one another; others starting fights just to create chaos.
So, a new fad among spoiled bored teenagers, then?