New Delhi: As many as 22 children fell unconscious during the birthday celebration of a teacher in a south Delhi school on Wednesday, police said. The unconscious students of the government-run school in Mehrauli were rushed to  Safdarjung Hospital where they have been kept under observation, they said."Information was received that some school students became unconscious and they were rushed to the hospital. Police officials have reached Safdarjung Hospital where the students were under treatment," a police officer said.Initial investigation has revealed that the incident happened after a pepper spray went off after it was mistaken for a deodorant, the officer said, adding further probe was underway.