The incident occurred at Darbarpur village under Labhpur police station area.
"A gang of miscreants was making bombs on the outskirts of the village. Somehow the bombs exploded in the afternoon, killing four on the spot. Four others were declared 'brought dead' when taken to the hospital," district Superintendent of Police N Sudheer Kumar said.
The eight deceased were identified as local miscreants who were making crude bombs as a part of their preparation to continue an ongoing fight between two groups from the locality, he said.
Two of the injured were taken to Burdwan Medical College and Hospital in a critical condition while two others were admitted to another hospital.