The accident happened on McKinley and Garfield a little after five o'clock.
Investigators say about 25 Central Unified Elementary students were on the bus and when the driver slammed on the brakes to avoid hitting a dog.
Some of the kids hit their heads on the seat in front of them and complained of pain.
Paramedics treated eight kids on the scene then released them to their parents.
Another bus was brought in to take the rest of the students home.