The assault on the 23-year-old woman, whose male companion was also beaten, was so severe that she is still in a critical condition in hospital. One of those arrested is the bus driver.
Since the attack on Sunday there have been calls for action from the government which has now announced a series of measures intended to make Delhi safer for women.
Ban tinted windows
They include more police night patrols, checks on bus drivers and their assistants and the banning of buses with tinted windows or curtains.
Delhi police chief Neeraj Kumar said: “The fifth accused has been arrested in the rape case. His age is being verified before giving details. If [he is a] minor, we have to hold back his particulars as per law.”
Police said the woman and her friend boarded the bus in the Munirka area and were on their way to Dwarka in south-west Delhi after watching a film in a shopping centre in south Delhi.
Beaten and stripped
The student and the friend she was travelling with were beaten, stripped and thrown out of the bus in the attack. The woman has undergone two rounds of surgery since Sunday and remains on life support at Delhi’s Safdarjung hospital.