Police in the Indian capital say they have arrested a fifth person in connection with the gang rape on a bus of a young woman on Sunday.
Four people, including the bus driver, have already been arrested.
The 23-year-old woman remains in a critical condition in a Delhi hospital.
There has been outrage in India in the wake of the attack on the woman and her male friend. The government has since announced a series of measures intended to make Delhi safer for women.
They include more police night patrols, checks on bus drivers and their assistants and the banning of buses with tinted windows or curtains.
“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,” Delhi police chief Neeraj Kumar was quoted as saying by the Press Trust of India.
The men arrested in connection with the incident earlier also include a gym instructor and a fruit seller.
The woman has undergone two rounds of surgery since Sunday and remains on life support, doctors at Delhi’s Safdarjung Hospital said.
Angry MPs have demanded the death penalty for the rapists, and protests and candle-lit vigils have been held in the capital and elsewhere in India.
The woman and her friend boarded the bus in Munirka area and were on their way to Dwarka in south-west Delhi.
They were returning after watching a film in a shopping centre in south Delhi, police said.