The Chandigarh Police have registered a case of rape after a complaint from a girl that she was sexually assaulted by a man while returning home after attending the Independence Day function at her school here on Tuesday, police said.The victim, aged 12-13 years, was admitted to a government hospital here for medical examination and treatment.The man assaulted the Class 8 student of the Government Senior Secondary School, Sector 23, at the Children's Traffic Park in the same sector.Chandigarh's Senior Superintendent of Police (SSP) Eish Singhal and other police officers, who were attending the main I-Day function at Parade Ground in Sector 17, rushed to the spot.Police officials said the victim said the assaulter dragged her near a 'nallah' (seasonal stream) passing through the traffic park and raped her at knife-point.The incident happened despite Chandigarh being on high alert on Independence Day.Government officers, some of them having security, live in the vicinity of the main gate of the traffic park.The incident has happened in Chandigarh just days after the attempted abduction and stalking of Varnika Kundu by Vikas Barala, the son of Haryana BJP President Subhash Barala, and his friend Ashish Kumar.