Deputy Superintendent of Police S Jawahar said the old lady, R Muthammal (72) opened the wooden box, reportedly kept in front of her house by some persons, which then exploded, seriously injuring her.
She was admitted to the local government hospital, where her condition is stated to be critical
Top police fficials rushed to the spot. The services of sniffer dogs were also requisitioned.
Jawahar said it was too early to say if the material was a country bomb or not. However some batteries were found and only detailed investigations would yield anything further, he said.