At least six people, including two children, died on Tuesday aroumd 7 pm after a crude bomb exploded at Tsunami colony near Idinthakarai village that has been epicentre of protests against the Kudankulam nuclear power plant in Tamil Nadu.
Three houses collapsed due to the impact of the explosion.
Fearing arrest, all villagers fled Tsunami Colony as soon as police personnel arrived.
Bodies could not be identified as no villager was present to help the police.
A case has been filed against activist Udhayakumar, who led local campaigns against the Kudankulam plant. Some of the people killed in explosion are suspected to be activists of the People's Movement Against Nuclear Energy, which is headed by Mr Udhayakumar.
The police claim the blasts took place accidentally while bombs were being assembled at a house in the village.
Two live bombs were also recovered from the spot.
M Pushparayan, a leader of the People's Movement Against Nuclear Energy that is spearheading the protests, said the country bombs had nothing to do with their movement nor were their supporters involved in bomb making.
The village has witnessed massive protests over the last two years against the nuclear plant.
Some villages in this region are notorious for making crude bombs to target rival groups during clashes. Last month, a minor boy was arrested for possessing around 25 country-made bombs at the neighbouring village of Koothankuzhi.