I don't know that anyone is killed by the police for just one reason. However, being black does figure into how many police officers respond to certain people. Teenagers in a group....silly and annoying. Black male teens in a group...likely criminal. These stereotypes don't just go away because someone has a badge. I've known perfectly nice white folks who'd cross the street if a young black man was approaching from the other direction, but they wouldn't if it were a white young man.
Btw, the Implicit Association Test (link is included later) is a great way for people to discover their hidden race preferences. According to the stats generated by this tool, 80% of whites show a preference for whites. This means we attribute VIRTUOUS things to whites--words like love, peace, joy--and FEARFUL things with blacks--words like terrible, failure, and evil.
People like to pretend that they can live in culture where all the media around them constantly favors white in a variety of ways and they are somehow magically unaffected by it. We aren't...and neither are police officers. So, it's probable that no blacks were shot ONLY because they were black, it's equally possible that being black creates a kind of anticipated danger or anxiety in some cops that leads to trigger fingers and unfortunate deaths.
Here's the link if you want to take the test yourself:
https://implicit.harvard.edu/implicit/