Ex marine and gang of kids movie

Ex marine makes friends with local african american kids, but one day one of them is missing or something and he finds out he joined a gang so he goes on a spree trying to save him

it starts on the outside of the building in a parking lot, going into this massive apartment complex/tenements

he kills quite a lot of people, he gets shot up a quite a bit, once he makes his way to the leader’s room he’s lost a lot of blood and is extremely white in the face, sits down on a couch

then the kid with leader come out from a door, leader makes kid shoot marine in head, he slumps back over the couch and they walk off, end of movie