Police said the incident occurred this morning when the TMC worker Apel Sheikh, known to be close to the party's Bibrhum district unit president Anubrata Mondal, was sitting in his shop at Kumorpur village.
A gang of about 10, including TMC member Zahid Sheikh, barged into the shop and sprayed bullets at him killing him on the spot.
District Superintendent of Police Kunal Agarwal said a large police contingent rushed to the spot but none was arrested as yet.
Civic polls in the state, seen as 'semi finals' to the Assembly polls scheduled next year, would be held on Saturday. The results, along with that of Kolkata civic board, would be announced on April 28.