The incident took place at a college for girls in the Nazibabad police station area.
According to a police spokesperson, during a checking at the school, a mobile phone was found in the bag of the Class 6 student.
Angry over this, a female teacher beat her up. The teacher then made her remove some clothes and directed her to stand in the classroom for two hours in that state, the spokesman said.
After the girl's death, her family members protested at the school, demanding immediate arrest of the accused teacher, who is absconding.
SP (Crime) M P Verma reached the school and ordered registration of an FIR on a complaint from the family members.