A police officer said preliminary investigation revealed that the girl hails from Murshidabad district and belongs to the age group of 15-17.
It is not clear who accompanied her to the garden, which is now officially called Acharya Jagadish Chandra Bose Indian Botanic Garden, police said.
The girl could barely speak and was admitted to Howrah General Hospital. The doctors said that she could be questioned after her condition stabilises, the officer said.
The girl could only tell the officials that she hailed from Murshidabad after being taken to the hospital.
To a question if the girl was sexually assaulted as claimed by some tv channels, the officer said there was no confirmation in this regard so far and investigations were on.