The youth, who was carrying prasad, was hit suddenly by a speeding motorbike while he was walking past a bank last evening, the police said adding he died on the spot.
The girl, who was on the motorbike along with two other youths, fell off it when it hit the youth and was later arrested.
The other two, who had sped away, were arrested later after questioning the girl, the police said.
Local markets downed shutters today as a mark of grief.
Jalpaiguri superintendent of police Amit Javalgi said the police would take strict steps to control rising incidences of speeding by youths on the narrow streets of this busy town.