The death toll in Sunday's massacre by NDFB militants in Assam's Sonitpur district on Wednesday rose to 15 even as Chief Minister Tarun Gogoi announced a high level investigation into the incident.
An injured woman in the Gauhati Medical College Hospital (GMCH) in Guwahati died.
Gogoi, who visited the victims at the GMCH, announced a high-level probe into the incident.
Despite rise in extortion activities of the NDFB which created tension and violence, additional security forces was not deployed, Gogoi said.
On the activities of the NDFB as well as the ULFA, he said they had taken shelter in neighbouring countries like Bangladesh and Myanmar.
"The terrorist groups are never interested in peace in the state. Strong action will be taken against them," he said, adding the Centre had turned down the state's request for more forces due to elections in some states.
Gogoi said the existing forces in the state will be redeployed.