That sign on the post struck me on two counts. 1) "is not A accident" sounds weird to me. I think I still remember something I learned in elementary school grammar – the use of "a" and "an" in a sentence – it's got something to do with the letters/syllables that follow, right? and 2) why the message? who is it for, who is it from?
By the manner it was printed, it does not seem this is just another of those (vandalism) expressions of young idiots who will soon grow to become adult idiots! Y'know, those 'cannot-do-anything-good' spray-paint-can-wielding boys? This does not look like their doing. I think this means something else.
And what is police violence in this place anyway? Maybe there had been violent shanty demolitions in the area? Probably.
I still wonder... but oh well, the signs of our times!