The thing is the US has always been a fractured country. They call it the land of the free, IMO it couldn't be further from the truth. Yes they abolished slavery in what 1866, but anyone that has been to the US can see how segregated suburbs are compared to other western countries. Here in Australia most cities are integrated between all races of people. You could live next to an Asian immigrant, a black immigrant, an indigenous Australian etc and no-one bats an eyelid. In the US, most suburbs are primarily white, black or hispanic. There is no integration. White people don't go "downtown" as thats where the dangerous black people hang out etc.
These racial overtones have been there for decades if not centuries. Martin Luther King made his I have a dream speech 60 years ago in August yet has anything really changed from then until now. Nope not really. Still communities segregated by race, its slavery but in a different form.
These tensions have been simmering now for probably the last 20 years under our noses. It started when Obama became president and the black voters finally realised they have a voice in their country. It should have been a pivotal moment in time that allowed their country to integrate and finally pull its status forward into the country that they seem to think they are, but its actually done the opposite. Obama becoming President made the white upper / middle class scared that they would lose out in this revolution of sorts, so they armed themselves to the teeth. Look at the FBI stats on this, from when Obama was elected President in 2008 (he took office from 2009).
Then Trumpism kicked in and drove the division in society even further away from each other, leading to a nation that is essentially at war with itself.
Scary place to be and I don't see a way out of this for the US, they simply don't want to help themselves and are essentially sanitised the amount of killing they do amongst themselves.