Two Communist Party of India-Marxist Leninist (Liberation) supporters were killed by suspected activists of the banned Ranvir Sena, a private militia of upper caste landlords, in Bihar's Bhojpur district, police said on Wednesday.
Four others, including three women, were injured.
The miscreants sprayed bullets on a Dalit family while they were sleeping at Charpokhri village on Tuesday night, killing Devlal Ram and his son Ganesh on the spot, District Superintendent of Police Ajitabh Kumar said.
Devlal's another son has been admitted to the Patna Medical College and Hospital.
The incident might be the result of a struggle between the CPI-ML (L) and Ranvir Sena for establishing supremacy in Ara, the police said.