The Bihar government has asked the Central Bureau of Investigation (CBI) to investigate the murder of Brahmeshwar Singh, the chief of right-wing upper caste landlord militia Ranvir Sena, who was shot dead on Friday.
Singh was taking a morning walk on Friday when some unidentified gunmen shot him dead at Katira Mohalla under Nawada police station.
The news of his killing triggered violence in Ara, forcing administrations to impose curfew in the area after the incident on Friday.
Bihar Chief Minister Nitish Kumar had assured of a probe to track down the people behind the killing.
Nitish Kumar said: "We have appealed to all to maintain peace. There would be probe to find out the guilty. The perpetrators will be punished."
Supporters of Brahmeshwar reportedly created disruptions in the state by destroying public properties and burning buses. They even broke windows of Patna Rajdhani Express.
The banned Ranvir Sena was formed by Bhumihar Brahmin landlords. It was formed to curb the Dalits and other members of the scheduled caste community as well as the Maoists.
Ranvir Sena, which was dominant in the 1990s and were behind several massacres of the lower caste Dalits, was a spent force in recent years, but the killing could invite a reprisal and revive the old class enmity in Bihar.
From Bhojpur district where it was formed, the Ranvir Sena spread to Jahanabad, Patna, Rohtas, Aurangabad, Gaya, Bhabhua and Buxar districts.