"Each officer involved is now under investigation as the department tried [sic] to determine what went wrong"
Well, why would the officers involved be investigated? It was not their fault. The fault lies in management, who create (or in this case, apparently did
not create) policies and procedures. In, especially, law enforcement, the creation, training and execution of these polices and procedures can make the difference between life and death. The department in question probably never heard of real police work back-firing. Very provincial of them, IMHO. Of course, the source of this story is Detroit...city motto "We don't have a clue."
From, at least, the 1960's, the NYPD has used a simple, elegant, and (nearly) fool-proof system that allows plain-clothed officers to identify themselves to other non-uniformed and uniformed MOS (members of the service). The system is referred to as the "color of the day." At every muster, starting with the 0000-0800 shift, and continuing until midnight the next evening, a color is announced. Use of the color can be a bandanna, headband, hat, or even just the spoken word. A colored piece of cloth was often tied to the radio antenna of yellow cabs being used as undercover cars. It is used to allow telephone operators within the department to identify members who are calling to get confidential information. It is shouted during a confrontation between persons who each claim to be on the job, to avoid such unpleasantness as cop-on-cop gunfire.
See, for example,
https://en.wikipedia.org/wiki/Color_of_the_day_(police)While it is, as I said, "nearly" fool-proof, it is not a 100% perfect system. During the 1960's and 1970's, during those decades of civil unrest, several radio broadcast stations in the NYC metropolitan area, based in low-income neighborhoods and catering to those segments of the populace who traditionally delight in causing the police the most trouble, would announce periodically during their broadcasts, a message such as "Yo, bruthas, the pig be wearing green today" in order to corrupt the procedure in furtherance of their own nefarious agenda.
But, a slightly flawed system is better than no system at all, especially when lives are at stake.
Or a very tall Texas-style "20+-gallon" cowboy hat. 
