Four policemen were injured in the clashes. Cops have detained at least 12 people and registered case of rioting and destroying public property.
The girl is a student of Class 2 in a primary school run by the Municipal Corporation of Delhi (MCD). Her family has said in a police complaint that she was raped on Thursday afternoon.
The police have made no arrests yet but have detained a security guard and two male teachers of the school and are questioning them.
The girl was taken to hospital this morning, and doctors said she was in a stable condition, though traumatised. The police have sought the help of a non-government organisation to counsel the child as they try to get more details about the incident from her.
Expressing her shock at the incident, Delhi Chief Minister Sheila Dikshit has ordered better security and supervision in schools in the capital. She said, "The incident is inhuman and shameful. It is a shocking incident. The municipal corporation must strengthen their existing security infrastructure in the schools." (Read: Rape of minor is inhuman, shameful, says Sheila Dikshit)
There were widespread protests for days in Delhi after the brutal gang-rape of a 23-year-old medical student in a moving bus in December last year, demanding better security for women in the national capital. The police have made promises since, the government has brought an Ordinance on new laws on sexual assault, but cases of rape and assault of women have continued with alarming regularity in Delhi.