Different cities; completely different dynamics. Speaking about Chicago, where I've lived for four decades since grad school (in the city and mostly in the near-west suburb bordering the high crime Austin neighborhood):
The issues in Chicago -
1) Gang dynamics of the last decade or more. We used to have a few super-gangs controlling drugs and crime in different parts of the city. Over the years, those gangs were busted up. So now we have "micro"-gangs ...much smaller gangs controlling much smaller turfs, which leads to more contact points - and friction points - with other gangs. Ironically, the gangs no longer have accepted standards of conduct. I'd argue, for example, that the idea of shooting up folks leaving a funeral service, as recently happened, would not have been tolerated 20-30 years ago by the gangs. That would have been "bad for business."
2) Social media. Gangs use social media to inflame the tensions and, and the violence is an effort to right the perceived wrongs committed there.
3) Guns. Too much collateral damage is occurring because of the advanced weaponry of the gangs ...pull a trigger and send a spray of bullets all around. Hitting your target is optional. This is a federal issue of gun control. Yeah I went there.
I don't see how sending in federal troops helps the situation, other than magnifying the "police state." Send in more teachers; send in more social workers (elements of defunding the police) ...address the root causes of education and opportunity. Even with effort, it could take a generation to adequately improve things.