PRETORIA, South Africa — Oscar Pistorius was taken away in a police van with barred windows Tuesday to start serving a five-year prison sentence for killing girlfriend Reeva Steenkamp. Delivering her sentence, Judge Thokozile Masipa cited the "gross negligence" the double-amputee Olympic runner showed when he shot Steenkamp multiple times through a toilet cubicle door in his home. Pistorius, who had cried and retched during his trial, was unemotional as he stood to hear his sentence.