By Manikant Thakur BBC reporter in Patna

The authorities in India's northern state of Bihar say six people have been killed in a gun battle between supporters of high-caste Hindus and communist activists.

Police say the clash took place on Friday in Kurmuri village, about 100 kilometres (60 miles) from the state capital, Patna.

The combatants belonged to the "Ranvir Sena" militia and supporters of the Communist Party of India (Marxist-Leninist) respectively.

The Ranvir Sena is a militia that has traditionally supported "high caste" landlords in rural Bihar.

The CPI (ML), on the other hand, enjoys considerable support among the area's "low caste" communities.

'Lawless'

Members of the militia have engaged in bloody clashes with CPI (ML) activists in the past too.

A senior police officer said an old feud seemed to have triggered the killings on Friday.

The officer said Ranvir Sena members gunned down two CPI(ML) supporters on Friday morning following which CPI (ML) militants killed four members of a family of Ranvir Sena supporters.

The authorities say more than 10 people have been arrested to prevent further violence.

Bihar has the reputation of being one of the most lawless states in India.