NEW DELHI: The four men convicted of the gang rape and murder of a Delhi woman on December 16, 2012 were hanged in the darkness of pre-dawn on Friday, ending a horrific chapter in India's long history of sexual assault that had seared the nation's soul.

Mukesh Singh (32), Pawan Gupta (25), Vinay Sharma (26) and Akshay Kumar Singh (31) were executed at 5.30am for the savage assault in an empty moving bus on the 23-year-old physiotherapy intern who came to be known the world over as Nirbhaya, the fearless one.

This is the first time that four men have been hanged together in

, South Asia's largest prison complex that houses more than 16,000 inmates. The executions were carried out after the men exhausted every possible legal avenue to escape the gallows. Their desperate attempts only postponed the inevitable by less than two months after the first date of execution was set for January 22.

They were hanged at 5.30am, director general of prison Sandeep Goel said.

After raping and brutalising the woman, the men, one of whom was a juvenile at the time, dumped her on the road and left for dead on the cold winter night. Her friend who was with her was also severely beaten and thrown out along with her. She was so severely violated that her insides were spilling out when she was taken to hospital. She died in a Singapore hospital after battling for her life for a fortnight.

Six people, including the four convicts and the juvenile, were named as accused.

While Ram Singh allegedly committed suicide in the Tihar Jail days after the trial began in the case, the juvenile was released in 2015 after spending three years in a correctional home.

The road to the gallows was a long and circuitous one, going through the lower courts, the High Court, the Supreme Court and the president's office before going back to the Supreme Court that heard and rejected various curative petitions.

The death warrants were deferred by a court thrice on the grounds that the convicts had not exhausted all their legal remedies and that the mercy petition of one or the other was before the president.

On March 5, a trial court issued fresh death warrants for March 20 at 5.30am as the final date for the execution.