A family of "gundas" in my area

I'm writing this at 4am on New Year's cause honestly I've seen enough. Just to give you guys a background, I reside in a goathan - so it's a chawl like area. We have a lot of North East Indians living on rent. So there's this family of four that always has fights with people, they are v abusive and have some sort of pechan with the cops. Most of the times they target these North East Indians or anyone that seems to be weak or has less influence.The younger son - let's call him C3, got into a fight with a North East Indian some time ago. C3 "broke" the other guys head. Since it's dark, I couldn't see the other guy so I do not recognise him. But he was sitting and puking. I'm just too worried about that guy. Some of his friends arrived and took him home but it looked like he needed urgent medical care. Now ik most of you would suggest that I call the cops - which I did but everyone went away. So I called the cops back and asked them not to come cause what would I even tell them? Idk who the injured guy is. And I'm trying to stay out of everything, because C3 had a fight with me on Christmas. Now let me explain why he had a fight with me, and sorry in advance cause it's gonna be a long read. He was high - not alcohol, but drugs. I know it was drugs cause his friend told me he's tripping right now, he's flipped on something,etc. There was a BMC sweeper guy doing his usual job of cleaning the road at 8am. This C3 guy came out of nowhere and started abusing the sweeper and told him not to clean the roads. When I started recording this behaviour of his, he started abusing me. He kept grumbling and using the most disgusting words for about 10 mins until a neighbour got in between and tried to calm him down. He threatened that he would burn my house down, f**k my happiness, etc. He's pissed about the recording cause about a month ago I recorded his brother C2 hiting a man with a pipe. He even hit the man's wife when she tried to save her husband. This video was shown to the cops and that stupid woman told them I shared the video. So now they're very aware that I record them. Their parents are no good. I remember back when I was in school, about 7 years ago, the father and the elder son C2 hit a guy so much that his face was completely disfigured. So yeah, I've had enough of these guys. I've not even mentioned all of the fights cause there are just way too many. Idk what can be done. Cause everytime it's just me and my mom who try to stop their fights. I've literally gotten in between so many fights. No one else in my area seems to care about these things. Or maybe they care but they're just too scared to do anything. I think they're gonna keep doing this until someone loses their life. On a side note guys, I wanna install cctv cameras outside my house. Obviously this is the main reason. Apart from this family, my area is pretty safe. Please help if you know any affordable cctv installation services. Thanks for reading.