Dallas — A mother from Dallas is calling for her daughter's school bus driver to be fired after obtaining video of her child being violently bullied on the bus. The video shows the 5-year-old girl being assaulted multiple times.

First, by an older student sitting next to her, and then by a student from behind. Then, the boy moves closer to continue his barrage of slaps. At some point, the girl screams for the bus driver to help. But no help ever comes.

"I lost my mind. I couldn't believe what I saw. I couldn't believe that there was an adult there that could have stopped it," said Audrey Billings.

The incident happened last November, during a 45-minute commute from the girl's Dallas public charter school. At one point during the assault, you can hear her crying.

"He heard cries of help and he chooses to do nothing and it could have been stopped within the first two minutes of the attack," Billings said.

The abuse ended after around 12 minutes, with her grandmother picking her up at the bus stop.

"I think the bus driver needs to be removed. If he didn't protect my child, is he going to protect anyone else's?" Billings said.

She told CBS News her 5-year-old daughter no longer takes the bus. In a statement, the Dallas School District said it has changed the driver's route and said it takes the safety of its students seriously.