Some enities were killed immediately (Creepers, Skeletons and so forth), Everyone else turned into the undead... A Zombie. Various kinds of Zombies have assumed control over the Minecraft World, Each type will have it's own attributes, it could be speed, strength or something different, In any event on the off chance that you see a Zombie... Run. Using the Flare Gun will make things a little tricky for you now, As it has been pointed out the Flare Gun loot is a little OP, So instead of editing the loot drop over and over again. Zombies will now spawn in a very close proximity to you when using a flare Gun, This is to give the illusion that the Zombies have been attracted to the sound of a Flare getting shot.