Chief Minister Tarun Gogoi said 12 died in police firing, one in a fire and six others in violent clashes.
About 70 others were injured in the violence in Assam, which began Tuesday when individuals attacked polling places, Press Trust of India reported.
The army held a flag march Wednesday in the areas hit by the violence to combat any additional protesters, Press Trust of India said.
Gogoi said 100 houses were burned, and residents fled their homes and are staying in relief camps.
Gogoi said he recommended a Central Bureau of Investigation investigate and a judicial inquiry look into shortcomings of the government.