NASHVILLE, Tenn. (AP) — Students and administrators raised concerns about a Tennessee school bus driver’s behavior behind the wheel in the weeks before a crash that killed six children. Police have charged driver Johnthony Walker with vehicular homicide after the Chattanooga crash. Federal authorities said Walker was driving off the designated bus route when he wrecked on a curvy road while carrying 37 children on their way home from Woodmore Elementary School.