Urban Justice (2007) on Netflix

Plot summary

In Los Angeles, two gangs, the Hyde Park Gang under El Chivo and the East Side Gangsters under Armand Tucker, are at war. Vice cop Max Ballister takes a call he believes is from his informant, Gary Morrison, leaves a dinner with his wife, and is shot dead. Max's father Simon, a martial arts expert with a past in covert work, moves into the neighborhood where his son died. His landlady, Alice Park, who runs a liquor store, helps him. Simon starts asking questions of the people around him, and his search brings him up against members of both gangs.