A bonsai cat would never be capable of this -
Two stray cats attacked three people after they got into a house when the front door was open. One women suffered scratches and she was bitten on both ankles, both knees and on her left calf. After calling for help, she told the officer it happened when the two cats entered the residence and attacked her for no reason. The other woman was bitten on the right calf.
After talking to the women, the animal control officer went to his truck for snares -- his "cat catchers." Then he heard screaming from inside the house. When he ran back, he saw a young male with blood over his face. The cats had attacked a boy who had opened the bedroom door. He was bitten on his forehead, nose, left ear and right cheek.
http://www.boston.com/news/nation/articles/2007/03/14/stray_cats_enter_home_attack_women_boy/?p1=MEWell_Pos2