A nun in her 70s was gang raped by a group of bandits Saturday when she tried to prevent them from robbing a Christian missionary school in eastern India, police said, the latest crime to focus attention on the scourge of sexual violence in the country.

The nun was hospitalized in serious condition after being attacked by seven or eight men at the Convent of Jesus and Mary School in Nadia district, 80 kilometres northeast of the West Bengal state capital of Calcutta, a police officer said.

The men escaped and police are searching for them, said the officer, who spoke on condition of anonymity because he was not authorized to talk to reporters.

The robbers tied the school's security guards with ropes early Saturday and entered the nuns' room, where the women were sleeping. They took one of the nuns to another room when she tried to block their way and raped her, the officer said. The woman, the oldest nun at the school, is either 71 or 72, he said.

The men escaped with some cash, a cellphone, a laptop computer and a camera, all belonging to the school, the officer said. They also ransacked the school's chapel and holy items, the Press Trust of India news agency cited the archbishop of Calcutta, Thomas D'Souza, as saying.

Scores protest attack

Scores of angry students, their parents and teachers blocked a nearby highway and railroad tracks for several hours demanding swift police action.

Mamta Banerjee, the state's top elected official, strongly condemned the attack and ordered a high-level police investigation. D'Souza appealed to people to maintain peace and harmony in the area.

India has a long history of tolerance for sexual violence, but the December 2012 fatal gang rape of a woman aboard a moving bus in New Delhi caused outrage across the nation.

The outcry led the federal government to rush legislation doubling prison terms for rapists to 20 years and criminalizing voyeurism, stalking and the trafficking of women. The law also makes it a crime for officers to refuse to open cases when complaints are made.