On the night of December 16, last year, Ram Singh, Vinay, Akshay, Pawan, Mukesh and the juvenile had gangraped the girl in a bus after luring her and her 28-year-old male friend, who was also assaulted, on board the vehicle, which was later found to be plying illegally on Delhi roads.
The victim's friend, a software engineer, had fractured his limbs in the incident. The girl succumbed to her injuries on December 29, 2012 at a Singapore hospital.
The court relied on the dying declaration of the victim, forensic evidence, including finger prints, dental models, DNA samples and other medical reports of the convicts, electronic evidence and the statements given by them to the police after their arrests.
The judge also said that the presence of the convicts in the bus in which the crime was committed has been established through the location of their mobile networks.
Before pronouncing the over 230-page judgement, the judge thanked the Delhi Police, the prosecution team and the defence counsel for bringing the case to its conclusion.
After pronouncement of judgement, the girl's family members, who were present in the court, said, "The day they (convicts) will be awarded death penalty, justice will said to be done."
Defence lawyer A P Singh alleged the verdict has been delivered under pressure and the four men will now be punished for the offences which they have not committed.
Advocate V K Anand, who appeared for Mukesh, said he will appeal against this conviction in the superior courts as he was only driving the bus.
Mukesh's mother was seen crying in the court while the other family members refused to speak.
Today's decision comes ten days after the juvenile accomplice in the case was sentenced to three-year term at a detention centre after being held guilty by the Juvenile Justice Board of gangrape and murder of the paramedic and robbing a carpenter before the incident.
The trial in the robbery case against the four is on in another court.
Before the judgement was to be delivered, police did not allow several mediapersons to enter the courtroom which led to heated arguments.
Extra police force had to be called in as journalists argued with police personnel to secure entry in the room, which had to be cordoned off in the wake of commotion.
As per the Delhi High Court's March 22 order, only one person each from national dailies and news agencies was permitted in the courtroom after checking their credentials and scribes from electronic media were not allowed to enter.
Outside the court complex, around 40 youths had gathered claiming to be from '16 December Kranti', a Facebook-based group, demanding death penalty for all the four convicts.
The court had reserved its judgement on September 3 after the prosecution and the accused concluded their arguments.
During the trial, Mukesh had admitted his presence in the bus, while Vinay, Akshay and Pawan had denied the charges levelled against them.
The case led to formation of fast track courts for trying sexual offences two weeks after the incident.