People interested in solutions should look to studies of different types of interventions. My usual example is the extremely effective Violence Reduction Unit:
"The results were remarkable. Among the 200 gang members who became directly involved with CIRV, violent offending fell by almost half, according to a 2011 study. Weapon possession was down 85%. Even among gang members who had not attended a call-in, violence had fallen by almost a quarter."
http://www.actiononviolence.org.uk/
https://www.theguardian.com/uk-news/2015/apr/06/glasgow-murd...
"The results were remarkable. Among the 200 gang members who became directly involved with CIRV, violent offending fell by almost half, according to a 2011 study. Weapon possession was down 85%. Even among gang members who had not attended a call-in, violence had fallen by almost a quarter."