The killing of unarmed black people by police happens so regularly now that I can't keep the details straight from one to the other. Of course we only hear about some of them, and we mostly only hear about the situations with video evidence or other details which make it difficult for the police to credibly claim that they were threatened.
But even being threatened shouldn't be enough for a summary execution. It's their job to know how to de-escalate situations. That might not always work, but often it seems they don't even think about trying.