A former school bus driver in Tennessee was found guilty Thursday of causing the crash that killed six children. A Chattanooga court convicted Johnthony Walker, 25, of six counts of criminally negligent homicide in connection with the November 21, 2016, accident that killed Zoie Nash, 9; D’Myunn Brown, 6; Cordayja Jones, 9; Keonte Wilson, 8; Zyaira Mateen, 6; and Zyanna Harris, …