They first objected but as the men continued to harass them, one going as far as touching the girls inappropriately, one of the girls removed her belt and started beating the men...the other girl joined with her fist. Another passenger filmed the whole incident on his mobile and uploaded it on Youtube.
The girls, 22-year-old Aarti and 19-year-old Pooja, later spoke to BBC Hindi about the incident;
"The men started to abuse me and touch me. I told them 'if you touch me again, you'll get beaten up'. They called a friend on the phone and told him to 'come over because we have to beat up some girls'," Pooja said.
The girls said they decided to take on their attackers when other passengers on the bus did not come to their help.
"No one came forward in the bus to help us. So we took out our belts in self-defence [and hit the men]. If only the other passengers had helped us, we would not have needed to retaliate in this way," she said.
The sisters said the men pushed them out of the bus when it came to a halt after some distance and attacked them again. They said they retaliated by throwing stones at the men who then finally left them alone.
Sexual harassment is a big problem in India, with so many rapes reported weekly. Watch the video of the bus beat down below..