For the people you describe, there are basically no social services. The typical cycle is: 1 - police arrest them 2 - if they seem psychotic or mentally troubled they get dropped off at an ER 3 - the social workers at the ER (mostly) unsuccessfully try to find a place for them at a mental health provider 4 - eventually they get released by court order 5 - cycle repeats

I have friend that is on the front line as a social worker. Any time one of these prominent incidents occurs, I make sure to ask if she knows the perp. And about 50% of the time they are a former patient that she couldn't find a spot for at a mental institution.