Police have blamed the recent attacks on the United Liberation Front of Asom (ULFA), which has been fighting for the independence of Assamese people since 1979.
Attacks have increased since Indian authorities called off peace talks and a six-week temporary truce with the group in September.
The ULFA has not claimed responsibility for the attacks.
Most of the dead in the recent attacks are migrant labourers from other Indian states.
At least 10,000 people, mostly civilians, have died in Assam in fighting between government forces and the separatist groups such as the ULFA and the National Democratic Front of Bodoland, which demands autonomy for Assam's tiny Bodo ethnic minority.