A massacre of tribal settlers that left at least 62 people dead in Assam has triggered a wave of violence in the northeastern Indian state, resulting in nine more deaths.

At least five people were killed by police gunfire after plantation workers angered by Tuesday's killings defied a curfew and surrounded police stations in Sonitpur district, private television channel NDTV said.

Two Bodos were also killed by villagers and several houses torched in Kokrajhar district. Two others were hacked to death in Chirang district, said the Times of India newspaper.

Some protesters also set fire to shops on Wednesday and others blocked a railway line and roads.

They didn't even spare women and children. - A police official in Assam state.

Tuesday's massacre of civilians, including women and children, have been blamed on armed fighters from the National Democratic Front of Bodoland. The group has been pressing for self-rule for members of the Bodo tribe, who they say are being marginalised.

Survivors of the attack on villages in Kokrajhar and Sonitpur districts say the attackers came on foot, armed with assault rifles and dressed in military uniforms.

"They didn't even spare women and children," said a police officer, adding there were at least 10 women among the dead in Tuesday's violence.

At least 13 children were killed.

"Police believe that this attack was planned. The gunmen reportedly fired indiscriminately on these villages that are largely populated by people know as the Adivasis," Al Jazeera's Karishma Vyas, reporting from New Delhi, said.

The Adivasis are a mix of Hindus and Christians and many had been preparing for Christmas when the attack took place, survivors said.

Indian security forces launched a campaign last month against the rebels in their remote hideouts, prompting a threat from them to target settlers.

Culture under threat

Some members of the Bodo community say their identity, culture and language are under threat of being overrun and the only way they can preserve it is through self-governance.

The rebels say they are fighting for a separate homeland for the indigenous Bodo people. They complain that the tea-growing state has been flooded with outsiders.

Lalit Gogoi, deputy commissioner of the worst-affected Sonitpur district, said the army had been put on standby and a dusk to dawn curfew imposed.

The single hospital in Sonitpur was crowded with scores of people with bullet wounds.

Assam is one of seven states in India's northeast, a region bounded by China, Myanmar, Bhutan and Bangladesh. For long, residents have accused the central government of plundering its natural resources and ignoring development.