CHICAGO — A newly acquired video shows four people, at least two armed with machine guns, unleashing a torrent of gunfire in Chicago on Wednesday evening. The shots left a 14-year-old boy dead and at least three others injured. Later, a 16-year-old boy fired a gun at Chicago police officers as they investigated the shooting. He was charged yesterday with six counts of attempted murder of peace officers. The video, provided to CWBChicago by a source, shows four people walking across a vacant lot in the 4200 block of South Wells around 8:20 p.m. on June 1.