At least 13 people were killed in a pre-dawn separatist rebel raid in the Assam state, hours after another string of attacks killed 19 people and injured 25 others in what officials say is a targeted campaign against Hindi-speaking migrant workers in the state.
Police said heavily armed fighters attacked a group of brick kiln workers and fishermen near Ghormori Chapori, a sandbar located in Tinsukia district, about 590km east of the state's main city, Guwahati.
Officials have blamed the violence on the outlawed United Liberation Front of Asom (ULFA), which is fighting for a separate Assamese homeland.
Absar Hazarika, the district magistrate of Tinsukia, told AFP by telephone: "The attack was carried out before dawn with the militants raining bullets on the sleeping Hindi-speaking migrant workers."
The authorities in northeastern Assam state have sounded a high security alert.
Tarun Gogoi, the chief minister of Assam, said: "Security offensives against the militants have been intensified after the inhuman attacks on innocent people by militants."
On Friday, migrant workers were attacked in six separate locations in the eastern districts of Dibrugarh and Tinsukia. Again, the ULFA is suspected of being behind the attacks.
The rebels fired at shops and businesses and triggered an explosion near a tea garden staffed by workers from the Hindi-speaking northern belt of India.
The ULFA has demanded the expulsion of non-Assamese people, especially those who come from Hindi-speaking states who they say take away their jobs.
In 2000, the outfit killed at least 100 Hindi-speaking people in a series of well-planned attacks after vowing to free the state of "non-Assamese migrant workers".
The new bloodshed came days after Indian authorities called on the ULFA not to disrupt national games due for next month after the rebels threatened violence to stop them.