Here was the first thing you heard from every journalist rushing to be among the first to tell the story. "Police shoot unarmed black man."
Then there were other early-emerging stories, like the one that claimed the "unarmed black man" was retreating and had his hands up, but they shot him anyway. You know the media. This is what they're hearing, it fits their narrative of racist killer cops, and more importantly, it will bring about the one thing they want more than anything else in this world: Race riots!
So off they go with the early reporting. Never mind the cops' side of the story. Never mind if those first things you heard turned out to be true. Run with it first and keep an eye on where things go.