The incident was reported from Gautampuri and the victim has been taken to AIIMS Trauma Centre where doctors said her condition is stable.
One person, the caretaker of the toilet, has been arrested while 22 others were detained for questioning, a senior police official said.
"The girl was found injured. We are awaiting medical examination report through which only we can ascertain whether she was sexually assaulted," the official said.
The girl lived in the slum cluster in Gautampuri and was attacked inside the toilet cpmplex nearby.