The incident took place in Nadia district. The mother has been arrested while others are in hiding.
Mampi Ghosh, 17, was killed by her family members including her father and brother. We have arrested the mother and a search is on for the other offenders, Additional Superintendent of Police Arindam Chowdhury said.
The Class X student reportedly had an affair with a daily wage labourer.
On finding the girl in the labourer's house Monday morning, the enraged family members repeatedly attacked Mampi with sharp weapons and killed her on the spot.