Sujaya Basak, a student of Samudragarh High School, was returning home along with her friends in the Katwa Bandel local train when she was pushed off the train Saturday near Kalinagar station in the district, some 90 km from Kolkata.
"We have already interrogated two friends of the boy while his brother has been arrested and presented before a court," said Tapan Kumar Das of Government Railway Police (Kalna).
The boy who stalked the girl had an argument with her in the train after she refused his proposal for friendship. He then dragged her and pushed her out of the running train, police said.
Family members of the girl have demanded exemplary punishment and also accused the police of inaction.
"The boy has been stalking my daughter for long. The police are yet to arrest him. Had the police taken my daughter to a hospital in time, she would not have died," the girl's mother said.
The incident created a huge outcry among the people who staged a protest in front of the Kalna GRP station, demanding immediate arrest of the boy, who is now untraceable and on the run.