The Dems should be careful of over-reacting. The GOP knows how to play these race-based incidents to their audience too.
It's bad. Let the corrective process happen. Focus on changing police operating protocols, not on damning individuals. The Dems won't win anything by putting one person in jail. They have to persuade the police not to use weapons in these situations across the board, not to behave in bullying ways when a person is subdued etc.