Police say the girl went missing April 15 and was found two days later by neighbors who heard her crying in a locked room in the same New Delhi building where she lives with her family. The girl was alone when she was found, having been left for dead by the man following the brutal attack, police say.
A 24-year-old man was arrested Saturday in the eastern state of Bihar, about 620 miles from New Delhi, in connection with the incident. After being flown to New Delhi, he was in custody Sunday and was being questioned, police said.
The incident came four months after the fatal gang rape of a woman on a New Delhi bus sparked outrage across India about the treatment of women in the country.
For the second consecutive day, hundreds of people protested Sunday outside police headquarters in the capital, angry over allegations that police had ignored complaints by the girl's parents that she was missing.
About 100 supporters of the main opposition Bharatiya Janata Party protested outside the home of the chief of the ruling Congress Party, Sonia Gandhi, demanding that the government ensure the safety and security of women and girls in the city.
The protesters also demanded that the Delhi police chief be removed from office and that police officials accused of failing to act on the parents' complaint be dismissed.
"Police and other officials that fail to do their jobs and instead engage in abusive behavior should know that they will be punished," Meenakshi Ganguly, South Asia director of New York-based Human Rights Watch, said Sunday.
Police said they detained more than 50 protesters when they tried to break down barricades on the road leading to Gandhi's house. The protesters were released after a few hours.
Police also placed restrictions on the gathering of more than four people on the main avenue in the heart of New Delhi after university students said they planned to hold a demonstration there later Sunday. Despite the police order, about 100 students gathered at New Delhi's iconic India Gate monument and held a peaceful protest late Sunday.
Sexual crimes against women and children are reported every day in Indian newspapers, and women often complain about their sense of insecurity when they leave their homes.
Prime Minister Manmohan Singh called for changes in attitudes toward women in India, where there has been a fierce debate since December's fatal New Delhi gang rape about the routine mistreatment of females.
"The gruesome assault on the little girl a few days back reminds us once again of the need to work collectively to root out this sort of depravity from our society," Singh said Sunday at a meeting with civil servants.
A day earlier, Singh had urged Indian society "to look within and work to root out the evil of rape and other such crimes from our midst."
The fatal beating and gang rape of a young woman aboard a moving New Delhi bus sparked outrage and spurred the government to pass tough laws for crimes against women, including the death penalty for repeat offenders or for rape attacks that lead to the victim's death.
But activists say that merely passing strong laws is not enough, and that the government has to convey its intention to crack down on crimes against women to its officials and the police.
"Enacting strong laws are simply a first step, but it needs the government to focus urgently on implementation if it is serious about protecting children and other victims of sexual abuse," Human Rights Watch's Ganguly said.