They should just stage a walk-out, What Difference Does It Make!
I would imagine that the homicide rate of police officers in Chicago is probably somewhat less than that of the overall population of the city, seeing as how they are about the only people who are 'legally' armed.
Of course, the dirty secret that can't be talked about regarding chicago and all these other high-murder hell-holes, is that the murders are talking place within a very small segment of the population.