Late Monday, police claim to have arrested two accused in the rape case even as doctors claiming they had never seen a victim of sexual assault subjected to "such brutality".
TV reports suggest third arrest has been made in the case.
"We performed several life-saving procedures on her within an hour of her being brought to the hospital around 3am. Her injuries were severe and she has lost a lot of blood," said a senior doctor at the hospital.
The victim had reportedly lost nearly a litre of blood and had severe internal injuries.
"Her intestines are damaged; the blood supply to her intestines has been severed. It looks like she was assaulted by a blunt object as her face also bore injury marks," said the doctor.
The life-saving surgery lasted for more than four hours in the morning. Doctors tried to repair her intestines and other damaged organs and tissues.
"Her injuries are fatal. Though we are pumping her with the strongest of antibiotics possible, sooner or later gangrene is bound to set in. She is in a very bad shape," the doctor added.
The medical staff present at the hospital, when she was brought in, described her condition as "horrifying".
"She was in a pool of blood but conscious. There was blood all over her face. I cannot even imagine the agonising pain she must be in," said a nursing assistant in the hospital who wished to remain anonymous.
Sources in the hospital told Hindustan Times that it seemed at least four people were involved in the crime, as different semen samples were found on her.
The victim, who is a paramedical student, was doing internship at one of the private hospitals in the city.
Twitterati reacts
@namitabhandare -- 4 arrests are not enough. Cancelling the bus owner's licence is not enough. He should be arrested, made culpable too. Need fast-track trial (as in Guwahati), max punishment to deter future crimes against women #DelhiRape
@Snaggletooth_00 -- A separate crime cell in each state, specifically to deal with rape. Separate courts, separate laws. Drastic? Well, it's time.
@Prakash_Sharma -- Of course police can't be everywhere. But there has to be a fear of law. That has to be omnipresent. #DelhiRape
@anushreekejriwa -- Wake up to see the TL filled with a gang rape news in #Delhi. I wish Mayans stand corrected for the sake of us girls in this city.
@iCASumit -- "Gang Rape in Moving Bus in Posh-area of Delhi" Each word of that sentence is a mockery of evolution of human civilisation.
@KhabariGirl-Repeated #Delhirape is a clear cut example on political unwillingness towards law enforcement in Delhi. #DelhiIsNot4Women
@iamvishalchopra-- We touch mothers feet at home and then outrage a girl's modesty outside! #delhiRape
@nehamahendra6 -- Girls should stop 'exposing',eating junk food, speaking and stepping out of their homes. Then rapes will reduce no? #DelhiRape
Till December 15 this year, 635 cases of rape were registered across the city and despite the fact that there are still 15 days left for the month, the number of rape cases are highest in six years.
Cases of molestation have also seen a rise as 653 cases were reported in 2011 against 601 cases in 2010.
Defending their position, the police claimed that in majority of the rape cases the victims are known to the accused and thus, it is difficult to prevent the crime.
"Another important factor about rape and molestation cases is that in most incidents, the accused are known to the victim or her family. In all the rape cases (except 14) reported in 2011, the accused were known to the victim and had committed the crime for the first time," a senior police officer said.
Another senior officer claimed that in order to enhance confidence of the public, especially women, special measures have been introduced. "These include creation of predominantly women staffed police stations at north and south campuses and deployment of PCR vans near girls colleges," he added.
There is also a women's help desk at every police station and at regular intervals, the DCP — who is also the nodal officer — conducts self-defence training for women.
According to National Crime Record Bureau (NCRB), in 94 per cent of the rape cases across the country, the offenders were known to the victims and 10.6 per cent rape victims were under 14 years, while 19 per cent were teenagers.