Angry guardians on Friday protested at a school here after parents of a four-year-old girl student and doctors said she was sexually abused by a teacher and perhaps more men.

The girl, studying at the high-profile GD Birla Centre For Education in south Kolkata's Ranikuthi area, was profusely bleeding when she returned from school on Thursday, the girl's father said. She was rushed to a hospital.

"We initially thought it was some infection. We took her to the doctor who said she was physically abused. My daughter is still in a lot of pain," the father said.

A lawyer for the victim's family said the girl was lured into a toilet and sexually abused.

"She was shown a chocolate and lured inside a school toilet where one or more men abused her. The girl was shown pictures of four suspects. She has identified two men, one of whom is her physical education teacher," the lawyer said.

Furious parents of the school students on Friday stopped the school buses from entering the premises and demanded the removal of all male teaching staff.

They also told the school to ensure security for the children, including by putting up CCTV cameras.

Police said they had received the complaint.

"Our primary focus now is to arrest the accused. We will further look into the security measures in the schools," a police officer said.