A number of crude bombs exploded at Lokpur in Birbhum district early on Thursday but there was no casualty.
A senior police officer said several bombs went off in a courtyard of a construction at around 2 am triggering panic in the village.
However, no body was recovered from the site nor was anyone found to be injured.
The area, a political turf of supremacy between the ruling Trinamool Congress and CPI(M) had also some abandoned coal mines and was near the Jharkhand border.
A section of locals said the bombs could have been stockpiled for blasting the mines and went off by accident.