This may (or may not) be similar.
I live in an area that has had it’s share of problems, but also has a neighborhood association that tries to stay on top of things as best they can. There is a park across the street from me, and it is off limits after dark, and there is also a curfew for minors. The other night I got home after dark, and decided to go for my evening walk (as I often do). There is a bench in this park on one of the corners at a intersection (park is square, surrounded by four streets, one block each), and before starting out, I noticed some individuals walk across the park and take up residence on the bench (about three, maybe four of them). Realizing that my path would take along that corner of the park, I had a decision to make. Before continuing, I found a discrete place from which to call the police and alert them of the after hours violation, explaining that I had been instructed to do so by the head of the neighborhood association. I then began my walk, and as I approached them, I aimed my flashlight in their general direction just so I wouldn’t alarm them by passing by (they were probably about 20 ft away). I heard one of them comment on the ‘bright light”, and another one turned to stare (he was the one with the basketball). I made sure to keep an eye on them and continued on my way.
A couple years ago, there was a two to three week period when they was a heavy presence of drug dealing on that bench/corner. It's been clear for some time now though.
Keeping the neighborhood clean is a never-ending battle. One must not expect to get rid of today’s trash, and think there won’t be more next week.