Two Philadelphia cops shot and killed a black man, Walter Wallace Jr. But it does not seem that they rushed to kill.

He walked towards two cops while carrying a knife. They did not shoot immediately; they shouted at him to drop the knife. This is not a fabricated excuse; the article says it was visible on video.

The article does not say how far he was from them when they shot. Perhaps they didn't need to shoot. Perhaps they could have used a taser instead of a gun. Perhaps they could have tackled him and grabbed the knife, or talked him down. Perhaps medical personnel could have talked him down.

I think the death was probably avoidable, but that doesn't mean those cops had no grounds to shoot.