Teen quizzed over brutal bus attack

A 15-year-old girl has handed herself into police over the brutal gang bashing of a young mother on a Melbourne bus at the weekend.

The teenager, from St Albans, contacted Victoria Transit Police and was interviewed at Sunshine Police Station, 7News can reveal.

She is expected to be charged with causing serious injury.

The victim was a 26-year-old Frankston woman who was on board a NightRider bus in Melbourne's CBD in the early hours of Sunday morning.

It is alleged the victim, who has a newborn baby, was beaten unconscious after she complained to the driver about a rowdy group who had boarded the bus because they were being boisterous and knocking into other passengers.

After she complained, one of the women in the group threw a drink over the young mother then punched her in the face, police said.

Other group members then allegedly dragged the woman to the ground where they punched and kicked her body and head until she was unconscious.

Several other people had also complained to the driver about the group, which was standing in the aisle because the bus was full.

The group fled after the bus driver opened the door on Swanston Street.

The victim was treated at the scene and taken to the Royal Melbourne hospital for treatment.

She has recovered well and was discharged last night.

Police say the group of six or seven males and two females boarded the bus in the city about 2.30am (AEST) on Sunday morning and are perceived to be of African appearance.