Even that unfortunate incident when they killed the teen was very much reactionary, as people have been throwing Molotov cocktails etc at them for weeks now.
Honestly, i do understand the perspective of the rioters. Not having a chance to improve your life would make me violent too, i think... But framing the police as racists acting out is misguided considering that most of the issues are social in nature and not caused by the police.
And this might be too nitpicky for such an emotional topic, but the term racism gets thrown around way too much. I think it's more akin to classism, as it seems like you're still gonna get discriminated against if you originate from the poor areas, no matter what the color of your skin is.