Six people travelling on a Czech tourist bus through France were injured when the vehicle came under fire, a prosecutor said on Sunday.Authorities gave no clue as to the motive for the shooting, along a highway near Drôme in the south-east.Initial investigations indicated the shot was fired from a hunting rifle.Prosecutor Alex Perrin said the injured were hit by shattered glass.The bus was carrying 75 tourists including children on a school trip."Five people suffered light injuries, while the sixth was more serious," Perrin told BFM TV.