You've got your priorities fucked up if you'd rather waste time on a killing spree than take whatever measures are necessary for your survival first.
People with advantages in that situation:
People that own and know how to use firearms, People that know how to land navigate with a compass and map, people that know how to fight and kill, people that understand and are experienced in wilderness survival. Those people will definitely have an upper hand... in fact there is a whole "survivalist" culture dedicated to it.
Add me to team food hoarding fatty.
If I caught on early enough, I'd try to get food and supplies first. Otherwise, I'd wait for the police to try to control the first large wave of looters then go in with the second as chaos descends.
I'd make sure to steal things like cigarettes and alcohol as well to store for potential future trade value, otherwise I'd just wait it out.
I'd do many things that were illegal, both for survival and pleasure.
But my first priorities would be, locking, loading, and holstering weaponry, gathering my survival supplies, rigging up my ruck, stocking up on ammo, acquiring an older model vehicle that ran without the aid of electronics (perhaps an old dirtbike) siphoning gas, a generator, setting up camp by building a hide, somewhere in the woods. Gathering firewood and building a Dakota firehole for water purification, cooking and warmth.
and then I'd go have some fun and go hunting for pleasure that would turn into food...
How is "setting up" any different from doing what I said, which is grabbing supplies and finding a safe location to stay at with weapons on hand?
I never mentioned what I would do afterwards because you asked us what we would do first, and you basically indicated that you'd do same thing as me. Duh.