Six people were injured when their bus was hit by gunfire as it travelled from Spain to the Czech Republic, prosecutor Alex Perrin told French broadcaster BFM-TV on Sunday.
The shooter, who hit the bus as it was travelling on a highway in south-eastern France late Saturday, has not been found, Perrin said.
The injuries were caused by glass that shattered when it was hit, the broadcaster said.
The bus was carrying 75 Czech tourists, including a school group, who had been on vacation to Spain. According to BFM-TV, the shots were fired by a hunting weapon. Perrin said there was no indication the bus was specifically targeted.
"Five people suffered light injuries, while the sixth was more serious," Perrin told BFM TV.