Caste tensions are widespread in Bihar

The attack happened in Chakwai village in the state's Nawada district, police officials say.

Three people were also wounded in the incident, which police say is a revenge attack, linked to recent violence between upper and lower caste militias.

Caste tensions are widespread in Bihar, long regarded as one of India's poorest and most lawless states.

Police say they have sealed off all roads leading out of Nawada district in an effort to trap the attackers.

The shooting was the result of rivalry between two groups - one led by Akhilesh Singh, representing the interests of Bihar's landowning classes and the other headed by rival Ashok Mahto, they said.

The attack was apparently in retaliation for the killing of two Akhilesh Singh supporters in a recent blast.

Thousands of people have died in decades of sporadic violence between different caste groups in India.