A virus that was "accidentally" released into the world claimed millions of lives all at once. Nobody expected it, not the government or the citizens. The government of a particular country wondered 'what had gone wrong', while the citizens wondered 'what sin they had committed to deserve such a horrible punishment from God'. Zombie, undead, living dead, runners, walkers, lurkers...they go by various names...the new inhabitants of the 'damned' world.