Police said the girl was pushed out of Yeshwantpur-Mysore Express train near Maddur, about 63 km from here, yesterday and fell 25 feet below on the dry river bed of Shimsha.
The girl has been admitted to the Mandya Institute of Medical Sciences, where she is being treated for injuries to the head, backbone and legs.
The four men have been arrested, Mysore Additional Superintendent of Police Rajanna said.
The girl, a tailor at a garment factory in Bangalore, was travelling to her hometown Mysore on leave to spend time with her grandmother when the incident took place, he said.