A woman has been arrested for allegedly beating up a four-year-old girl brutally and robbing her inside the lift of a residential building in suburban Trombay, police said on Thursday.

The incident came to light on Wednesday after CCTV footage of the incident was aired by some websites. Rizwana Begum, the accused, was arrested the same day under IPC section 394 (voluntarily causing hurt while committing robbery), a senior police official said.

In the 2-minute-long video, the woman is seen brutally thrashing the girl who is crying in pain. Begum allegedly snatched away the girl's earrings, the official said. Police recovered them from Begum after she was arrested. Further probe is on.