Authorities ordered an indefinite curfew in the area after the violence in the remote Gendamari village in the northeastern state's Goalpara district near the border with Meghalaya state, the Press Trust of India news agency reported.
The attack, blamed on members of the Garo National Liberation Army based in Meghalaya, targeted migrant workers as they played cards, the report said.
The rebel group has been fighting for a separate state since 2009 and has been blamed for several killings, kidnappings and extortions in the region.
Army and police personnel patrolled the area to enforce the night curfew.
A senior police official said the curfew would remain in force from 7 p.m. to 6 a.m. It was not immediately known how long the curfew would last.