A teenage girl living in a Catholic convent outside Bangalore city was raped and left unconscious by the perpetrators on Wednesday, authorities said after India's latest violation against a young woman.

The victim, a 16-year-old girl, was on the ground floor of the convent of the Sisters of Holy Nativity in Henner when the facility's doorbell rang, ucanews.org reported.

Church officials said the attack was symptomatic of the increase in rape crimes in India.

A friend of the girl and a senior nun were inside the convent.

All the young woman remembered was the suspects sprayed some substance on her face which left her unconscious, Bangalore Archbishop Bernard Moras said.

She was found in a gap between the walls of the building and the convent's compound outside. The victim was rushed to a nearby clinic, and moved to a hospital to receive further treatment.

Moras said the girl also recalled there were at least two persons who raped her.

Authorities said the incident is being investigated and police have so far made no arrest.

Police lamented that the attack was reported to them 24 hours later than the incident.

They said the timing was crucial because it would have allowed authorities to conduct a manhunt operation immediately, a police official said.

S. Siddappa, additional commissioner of police in Bangalore, also ruled out the likelihood of the attack being related to the girl's religious beliefs.

But initial investigation confirmed that the girl was raped following medical findings.

"It is the work of some criminals and nothing to do with any religious hatred," he said, noting the rape reflected the grim state of affairs in India. "It is part of a growing problem across India."

Moras said the convent staff members were in shock, which contributed to the delay in the reporting of the crime to the police.

Statistics from India's National Crime Records Bureau show that almost three people are raped every hour in the country.

In 2013, police recorded 24,923 rape cases, which included the rape of minors.

"The sad part is that the central issue of morality is going down in the country. People seem to be not taking rape seriously," Moras said.

On July 2, a six-year-old girl was also raped in a school in Bangalore. Police have arrested the suspects, a school sports teacher and an assistant, in connection with the crime.