Is this child in danger? What should and can I do?

A friend's family is really bad. On her visit her pregnant sister whipped a DSLite and several game cases at my friend's head because my friend would not feed into her sisters negative antics and because she told the pregnant sister that she didn't have time to deal with drama. My friend got up calmly and walked over to the pregnant sister, asking her in exact words infront of me, "What the hell is your problem?" The pregnant sister, age 17 proceeded to scream, grab my friend's hair and pull her head downward where the only way to get free would be to attack the abdominal region of the pregnant attacker. My friend refuse to do this even though she felt her neck cracking. The pregnant sister screamed that my friend was trying to kill her baby which it was very obvious that she wasn't, yet the father who isn't married to the pregnant sister and much older proceeded to come in and attack my friend. The father has anger management cles and used to kill cats for fun as a minor. It wasn't long before another sister, the mother and the step father joined in on verbally and physically abusing my friend, their own family. The mother has been diagnosed psychotic, bipolar runs in the family as well as several diagnoses of the like. The pregnant sister and the father were living in the house where prescription meds were being sold as well as weed. The house was filled with roaches, maggots, fleas and flies. the roaches were so bad that they were in the microwave and the refridge. At the time there was eleven cats, five dogs, two ferrets, and a rabbit in their tiny house. The pregnant sister just had the baby yesterday. The sister that was attacked now experiences severe back pain everyday. She also received a black and blue face, not just eye from the fight which we took a picture of (Back in May or June I believe). I was wondering if I should inform child protective services of the potential danger this baby is in. I would also like to add that following the family altercation my friend returned to her grandmothers home, where the siblings and mother then began threats and harment through the internet. I am very concerned for the newborn's safety.