BZMetru was rather dangerous. Mafia abounded, an entire district was ripped from the sky, and other sorts of generally bad things were happening to the general populace at large. Something had to be done. Well, not for everyone, but at least some people, right?
So, a group of thirty got together and drafted a plan. They would leave BZMetru forever, taking with them vital supplies. They would leave in groups of ten, and that would be how they would leave the city. Nice and simple. No more gangs, no more deaths.
So the first group left. They traveled up from BZMetru to the island of Mata Nui, got in a boat, sailed to Voya Nui, traveled down the Chute and settled in Mahri Nui. And then half of them were murdered by the gang that had been following them. And then the other half was killed by the local gangs.
The remaining twenty arrived, and unfortunately, didn't now just who was in each trip. So the two gangs lurked among them, pretending to be the friends of the others, stalking them, slowly picking them off, one by one.
Oh, did I mention that the good guys brought a Pyro along with them?