With what? Baseball bats maybe? It's Chicago, peaceable folks are not allowed to own the most effective means of self defense. Although that effectively doesn't really apply to the thugs willing to break the laws against vandalism or worse. (The next step after graffiti and rocks is firebombs). (Chicago bans handguns, Cook county bans "assault weapons", very broadly defined)
Baseball bats work in sufficient number as do fists. You just have to out do the cowardly scum in numbers and level of aggression.
Any sort of resistance would be an improvement over a passive, “look what they did to us, isn’t it terrible.” response.