The incident occurred at the junior high school at Sikandrabad town, 20 kms from district headquarter, in which the girl, identified as class III student Soniya was killed, said Superintendent of Police (city) Makhan Lal.
Over a dozen others, including children, eight of them seriously, were also injured in the collapse and have been admitted to a hospital, he said.
According to the SP, the school was being run in a very old building and was in a dilapidated condition, with a mound of debris also found on its terrace.