A 23-year-old student gang-raped on a bus in New Delhi, India, died Saturday after fighting for her life for 13 days following the brutal attack.

The woman died in a Singapore hospital where she was taken for treatment. She suffered multiple organ failure and a heart attack after the attack on Dec. 16, according to media reports.

"Despite all efforts by a team of eight specialists  to keep her stable, her condition continued to deteriorate over these two days," said Dr. Kevin Loh, the chief executive of Mount Elizabeth, the hospital where she was treated, according to the Daily Mail. 

"She had suffered from severe organ failure following serious injuries to her body and brain. She was courageous in fighting for her life for so long against the odds but the trauma to her body was too severe for her to overcome,"

The woman's dead outraged the nation and thousands of protesters stormed the streets of New Delhi for two weeks to demand the government to punish the aggressors and protect women. The government has promised to take action, but it has a bad reputation of not responding to issues related to women's safety.

Authorities worried about the reaction to the news of her death and sent thousands of policemen to the streets, closed metro stations and banned vehicles from some main roads in the heart of New Delhi, according to media reports.

Six Indian men were arrested and charged with murder Saturday in connection with the attack, according to Reuters. The maximum penalty for murder is death, police told the news agency.

The victim was returning home from a movie and had boarded a bus with a male friend on the night of Dec. 16 when six men, including the bus driver, allegedly beat them up and gang raped her, media reports say.

The men reportedly beat them with metal rods and repeatedly raped the woman for 1 hour. Media said a rod was used in the rape, causing internal injuries. 

The victims were thrown out of the moving bus and left to die. Reuters report that the male friend survived. 

"Hang the rapists, we want justice," read one of the placards shown by protesters.

"Stop violence on women," and "We want justice, nation mourns a brave heart," other signs read.