The incident occurred when students were trying to make their way up and down a narrow staircase when they were asked to shift classrooms during an examination at around 9am in the Khajuri Khas Senior Secondary School, officials said.
Chief minister Sheila Dikshit said a high-level enquiry has been ordered and action will be taken against the guilty.
The government announced compensation of Rs1 lakh and Rs50,000 each respectively to the next of kin of the deceased and the injured.
Some students said they were asked to shift classes as certain classrooms were water-logged due to incessant rains since last night. One the of the girls, going down the staircase, fell leading to the stampede.
Police officials investigating the incident said local residents told them that some boys allegedly barged into a classroom for girls students and might have resorted to eve-teasing.
Earlier reports said a rumour about electric charge in water led to the stampede but locals refuted it saying that the area had no power supply at the time of the incident.
"Some students were rushing up while some were running down the staircase to reach their classes as a result of which the stampede took place," Dikshit told reporters.
According to some students, the principal asked the boys to move into a first floor classroom for Class XI students as their own class was flooded.
Joint Commissioner (New Delhi) Dharmendra Kumar said all but one of the 27 injured students were girls.
He said, "there was a stampede when some of the children on the first floor were asked to come down while others were going upstairs. Apparently the staircase was very narrow. Most of the children got stuck there".
The injured have been admitted to Guru Tegh Bahadur Hospital. "Among the injured, the condition of five students is very critical. They are on life support system. Others are relatively stable and conscious. They are being attended by neuro-surgeons and orthopaedic surgeons," GTB Medical Superintendent OP Kalra said.
Hospital authorities said most of the victims of the stampede died due to suffocation and head injuries.
