New Delhi (AFP) - Five girls were killed and at least 30 other students injured on Thursday in a stampede at a secondary school in the Indian capital New Delhi, police said. Police said they were unable to explain what had sparked the stampede, only that the tragedy had occurred on a narrow staircase during exam time at the state-run school in northeast Delhi. A TV reported that the stampede was triggered when some students were ordered to leave a classroom over fears of floodwater. Other reports suggested the schools roof had collapsed. Some of the children on the first floor were asked to come down and others were asked to go up and apparently the staircase was very narrow, joint police commissioner Dharmendra Kumar told reporters. Five girl students were killed in the incident while 32 others were injured. At the local Guru Tegh Bahadur hospital, medical superintendent, O.P. Kalra, told AFP that 30 children were being treated including six with serious head and spinal injuries. They are in the critical unit, he said. The chief minister of Delhi, Sheila Dikshit, rushed to the school where anxious parents were gathered outside demanding answers. Some tried to force their way in, but were held back by police. This is such a tragedy for which I cannot give an explanation now, she told reporters, declining to comment on speculation about the causes. We deeply regret that five children have died. Other parents waited at the local mortuary, fearing the worst.