The Governor had retaliated. At first, he had released a truck full of walkers within the fences of the prison. When that didn't work, only resulting in the death of his daughter, he launched a full out attack. Multiple people died, mostly his own. But amongst them was Hershel, who he beheaded in front of his two daughters.

During the fall of the prison, lots of debris were flying everywhere and constantly dropping from above. Inevitably, a piece of debris fell on you, knocking you unconscious in the process. Luckily, Tyreese had found you on his way out and he picked you up, carrying you safely out of the prison.