Assam Chief Minister Tarun Gogoi said curfew had been declared in two places and a judicial inquiry would be ordered to find out if the protests against the elections were instigated.
"Violence was reported in 22 places. I agree the security preparations for the elections could have been better. I take full responsibility (for the violence)," Mr Gogoi said.
Assam Home Secretary Gyanendra Tripathi said eight columns of the Army, which is about 500 soldiers, have been deployed to help the police and paramilitary personnel maintain order in Goalpara, around 120 kilometres from Guwahati. Top state police officials are in the district and are monitoring operations. The situation is under control in Goalpara town.
The police said it has had to open fire because members of the Rabha Hajong tribe were burning down villages and attacking government officials. Most shops and other establishments have been closed with violence hitting the area; houses have been burned and roads blocked by trees.
The Rabha tribe wants autonomy in this part of the state and rejects government control. It believes that panchayats or village councils will undermine its own council's authority. But the district has reported 60 per cent voting in the final phase of the panchayat elections.
Mr Gogoi defended the elections and criticised the Opposition for blaming the government and not those who were disrupting the elections.
The chief minister has announced a compensation of Rs 5 lakh for the families of those killed in the police firing.
More than 10,000 people have lost their lives to unrest in Assam over the last two decades.