She saw the storm of debris, and knew Carrie could take care of herself. Firefly fluttered over the crowd, spotting a zombie reaching for an older man who had fallen on his back. She swooped down and swung with all her might, trying to visualize a T-ball or something to keep her mind off what she was actually doing. Her swing connected, and rotting corpses didn't hold together as well as they should. The head of the zombie popped right off and landed in the man's lap. She didn't have time to apologize, and he watched, dumbfounded as she flew off to find another member of the living dead.
From her low aerial view she could see that, though the majority were running away, there were others picking up weapons and fighting back. It made her happy, seeing the brave ones.