Fr. Greg Boyle has been working to reduce the terrible effects on people of gang activity for decades.
This Fresh Air segment originally aired in 2017.
https://www.npr.org/player/embed/563734736/563828471
His work is important, and his stories are both heartbreaking and inspiring.
His two books are worth a look. His first, Tattoos on the Heart, and his latest, Barking to the Choir.