Three persons were killed in a bomb explosion in the house of a villager in the Mangalkote area in Burdwan district early on Thursday.
The police said the explosion occurred in the house of Meher Sheikh at Dhorsona village shortly after midnight, seriously injuring four persons.
The police took the four injured persons to a hospital, but on the way Sheikh and his wife Asthia Bibi died while another person died later.
Burdwan SP SMH Mirza ruled out involvement of any outsider in the bomb explosion and suspected that Meher Sheikh and his companions were making bombs when the explosion took place.
The police also seized some bomb-making materials and ammunition from the house. Local Trinamool leaders alleged that Sheikh was having dinner with his friends at the verandah outside the house when somebody threw a crude bomb at them.
Mangolkote MLA Shajahan Chowdhury of the CPI-M, however, alleged that it was the result of an intra-Trinamool Congress clash.
The SP said a forensic team from Kolkata would be arriving later in the day to find out the reason for the bomb explosion.
Frequent violent clashes between CPI-M and Trinamool Congress workers in Mangalkote have been reported in recent times, specially after the TMC started gaining ground in the CPI-M-dominated area.