How can the problem of cops mistaking undercover cops for criminals be eliminated?

New York is having a rash of these problems lately. Recently, an undercover cop who finished his shift came upon a thief breaking into his car. The undercover cop chased after the thief with his service revolver drawn. When other cops saw a black man running with a gun, they called out to him to stop. At that point, apparently, the undercover cop turned to look at the policeman calling out and another policeman shot and killed him. It’s not all black on white. Recently, it’s been black on black, white on white, Spanish on Spanish. Reaction times have to be fast. What can we do to stop this? I have no idea. I just know it has to be stopped.