Because of timingand budgetary restrictions, that storyline will take place in the town of Jericho only, as opposed to in two additional locations a full-season order would have called for.
Inmates had been (very occasionally) killing guards for a long time, but the timing of the murders, and the fact that they took place in a climate already prepared to believe that even ordinary humanity was wasted on the criminal classes, meant that the entire prison was put on permanent lockdown.