Filmmaker John Singleton, whose directorial debut “Boyz n the Hood” told a gritty tale of gangs in South Central Los Angeles during the 1980s and ’90s, died Monday after suffering a stroke. He was just 51 years old. Singleton was the first African American—and the youngest person ever—to be nominated for an Oscar for best director, in 1992. In 1997, he directed “Rosewood,” a historical drama based on the 1923 Rosewood massacre, when a white mob killed black residents and destroyed their Florida town.