Two of the children admitted to hospital in Dhubri town died, the sources said.
They were identified as Manowar Hussain (10) and Rockybul Hussain (13), they said.
Four of the critically injured were referred to the Gauhati Medical College Hospital for better treatment.
Last night eight persons, including two women and two children, of the family had received 80 per cent burn injuries when a fire broke out as they were sleeping in their house at Santoshpur, a remote village under Chapar police station completely burning down their bamboo-tin house.