Two men and a seven-year-old boy were injured in a bomb blast on a bridge in Assam's Sibsagar town on Tuesday afternoon.
The police said the bomb, kept in a motorcycle, had gone off around 4 pm on a bridge over the Dikhow river injuring three persons.
The condition of a man and the boy is stated to be critical. They were shifted to Assam Medical College in Dibrugarh.
Senior police officers have rushed to the spot and the entire area has been cordoned off, sources said.