Smoke billowing near the site of the attack near Kokrajhar in Inida's Assam.

Unidentified armed men have killed at least 12 people and wounded dozens more in a busy market area in a town in India's northeastern Assam state, police officials say.

The attackers opened fire on Friday at the crowded market in Kokrajhar, a town about 220km west of the state's commercial capital Guwahati, Sreejith T, superintendent of police, told Reuters news agency.

 One of the attackers was reported to have been killed. But local news channels said 20 of the injured were in critical condition and the death toll was expected to rise.

Security officials in Assam were quoted as saying that three or four armed men were involved in the shooting.

No claims have been made but about three days ago, police arrested members of the National Democratic Front of Bodoland (NDBF), a local armed group in the same area.

The NDFB seeks to establish a separate state for Bodo tribe members staying in Assam.

In 2012 there were clashes between Bodos and mostly Bengali Muslim settlers that resulted in hundreds of deaths. Hundreds of thousands were displaced.

Source: Agencies