A mass shooting in Jacksonville, Fla., is being investigated as a federal hate crime after a White gunman killed three Black people at a Dollar General store on Aug. 26, authorities say. Just after 1 p.m., Ryan Palmeter, 21, opened fire with an AR-15-style rifle, killing Angela Carr, 52, Jerrald Gallion, 29, and Anolt Laguerre Jr., 19. Palmeter, who then fatally shot himself, left behind several manifestos detailing his “disgusting ideology of hate,” Jacksonville sheriff T.K. Waters said. The shooting took place on the day the 60th anniversary of the March on Washington, when Rev. Martin Luther King Jr. delivered his “I Have a Dream” speech, was being observed. In a statement, President Joe Biden said, “White supremacy has no place in America.”…