The police, the government and any other authority capable of intervention here are more petrified of being labelled racists than in fixing the problem.
The African community will just continue to claim that it's only a few bad apples and will readily introduce the race card if anyone dares to suggest that it's an African problem. "Young whites get involved in violence and no one bats an eye but everyone is very quick to point the finger at Africans". You know how it goes.
The thing is, Africans are a tiny percentage of the population and for them to be so involved in violent crime is an obvious pointer to much deeper issues.
How many social commentators do you hear addressing this issue? Anyone who dares is quickly silenced by the very people that we expect to protect us from such lawlessness.
Any response such as voluntary community patrols has the participants labelled as vigilantes and racists along with dire threats from the police and government about taking the law into ones own hands. Why, they'll even say such things as "if you are involved in vigilante groups, you will feel the full force of the law". Pathetic and gutless.
How gutless and cowardly. To avoid the issue and blame the victims. Unfortunately, it will significantly lots more violent acts, deaths and maimings before the authorities do anything. By that time the problem will not be something that can be nipped in the bud.