At least 11 people have been killed and four others wounded after armed men with automatic weapons opened fire in India's northeastern Assam state, local government officials say.

Eight people, including four women and three children, were killed in one attack in Kokrajhar district, about 220km west of Assam's main city of Guwahati.

"In both the incidents heavily armed militants of the outlawed National Democratic Front of Bodoland (NDFB) fired indiscriminately with automatic weapons, killing 11 people on the spot and injuring four more," SN Singh, Assam's inspector-general of police, told AFP news agency.

The NDFB is one of several banned rebel groups demanding a separate homeland for Bodos.

The police claimed that the incidents were not related to the just-concluded parliamentary elections.

However, unofficial sources in Kokrajhar said the villagers might have been targeted because they had apparently not voted in favour of a particular party and its candidate.

Confirming this, LR Bishnoi, a senior police officer who holds charge over the four Bodoland districts said while three persons were killed in the first incident in Baska district at around 7pm on Thursday, seven persons were killed at around midnight in Kokrajhar district.

In both incidents, the assailants, suspected to be members of a faction of the NDFB, used AK-series weapons, Bishnoi said.

While two women and a man were killed in the first incident at village Narsingbari under Baska's Anandabazar police station, six of the seven killed in the attack in Balapara village under Tulsibeel outpost of Kokrajhar's Gossaigaon police station were women.

The victims in both incidents were from the migrant Muslim community, the Indian Express newspaper reported.

Survivors of the attack in Kokrajhar described how a group of about 20 masked and armed men carried out the killings.

"We were asleep when gunmen barged into our home and sprayed bullets, killing my elderly mother, my wife and my four-year-old daughter," Siraj Ali told a local TV channel as he sat beside the bodies in a police station on Friday.

Seventeen people were killed in clashes in the same region of Assam in January and thousands of others fled their homes for fear of further attacks.