Three Mullins middle school students face assault and bullying charges, following a fight on a school bus. Police say the fight stemmed from an incident at school and carried over onto the bus.

The Mullins Police Department says the three girls assaulted 12-year-old twin sisters and their 13-year-old brother on the bus last week.

The mayhem before and after the fight was captured on the bus's on board video camera, which the victims' mother gave to NewsChannel 15.

Tahtianna Johnston says she cries every time she looks at the video of her three children being called names and taunted on their school bus. At one point, a crowd surrounded her twin daughters, Katlynn and Cheyenne.

The crowd gets louder and police say what you don't see on the video is three girls assaulting the twins.

13-year-old Brenden Johnston tried to help his sisters, but says he couldn't do much because of the crowd. The bus driver stopped twice, even getting out of his seat to try and get matters under control.

Police have charged two 13-year-old girls and a 14-year-old girl with third degree assault and bullying. Officers say they face a bullying charge because they incited others to join in the fight.

As for her children, Tahtianna says they did the right thing. "They were taught not to hit back. Two wrongs don't make a right. But I also told them you're not a punching bag." Her children were treated for their injuries at a local ER. Since the fight, Johnston transferred them to another school district.

The school plans to take disciplinary action against the girls charged in the fight.