"Police are now appealing for the woman who assisted the victim and anyone else who may have witnessed the incident to come forward, any information you have may assist with the progression of the investigation.
Greater Manchester Police said the another woman witnessed the horror and helped the victim off the bus.
A GMP spokesperson said: "On Wednesday 22 January, at around 7:15am, a woman got on the 607 bus at #Bolton Interchange.
"Thankfully, the second woman witnessed the incident and interjected, before helping the victim exit the bus.
At the second stop, a man and another woman also boarded the bus.
