A small city in #SoCal around four decades ago:

Local police have a young Hispanic man handcuffed. They walk him toward the police cruiser where they will eventually put him in the back and take him away. But they take out their clubs and start beating him for no apparent reason. One of the people in the neighborhood (a White lady, probably in her 40s) asks "why are you beating that man, he's not resisting?" and the police grab their guns and order everyone to get inside their homes.

The man's crime? He was high on pot and rear-ended a parked car.

I personally witnessed this, so for all those "it doesn't happen all the time" folks, you just need to live in a poor or minority neighborhood. Not every victim dies, nor is every incident caught on video.