The missing context here that no other comments have mentioned is that the violence in question here is almost certainly perpetrated by and against poor blacks. Race relations in the US--particularly those between the black urban poor and whites--are definitely not ideal. I'm sure you've seen media coverage of the Michael Brown shooting and related incidents.

It's a terrible situation that most people aren't motivated to do anything about because it, for the most part, only affects poor black people. The vast majority of Americans never experience any of this violence beyond seeing it in the news.