This is why I wish the mods would be a little more lenient with discussions on "end of the world" scenarios. I know people get carried away with these topics, but situations like this (LA riots) and the Katrina aftermath show us that these things can happen, even in this country. I also think these types of things are just interesting to talk about, but I can see how it can make us seem like a bunch of nuts (who have guns).
I also happen to believe we will likely see more situations like this in the near future - say ten years or so. I'm not going to go into my thoughts on why, as I dont want to hijack this thread.
To answer the question (before this one gets shut down), my reaction would depend on the situation.
As far as roving gangs and people getting killed, you have to defend your family by any means necessary.
If I felt it was only local and would be short lived, I would hole-up at home.
If It was more widespread and seemed more like a "TEOTWAWKI" type thing (mass rioting/looting, murders, collapse of local govt resources like law enforcement) I, with my family, would try to flee to my in-law's cabin which is pretty isolated relative to any major population centers. I would bring whatever food and other necessities I could quickly gather, and worry about getting more once we were out of harms way.
If I can't get out of Dodge, I guess I hunker down here with a shotgun, rifle (which I unfortunately do not yet have) and hopefully enough supplies like food and water to get me through until it ends or I can get out.
Luckily, where I live I think it would really have to hit the fan, nation-wide, for things to go that far down-hill.