A man with a history of threatening people with deadly weapons, was known to be a menace to the police and had moments before been in a scuffle with them. It appears that he reached for a knife, once again a deadly weapon, and was shot. There should not be any arrests. Probably not even a civil suit because the police action was justified.
If a white man had done the same thing do you think he would not be shot? It happens every day but you don't hear about it.
As for the guy with a rifle, do you really think it would be wise for police to try to shoot at a man, even one with a deadly weapon, in the middle of a crowd?