The attackers, identified as members of an upper-caste militia backed by rich landlords, fought a gun battle with several armed villagers for two-and-a-half hours until the residents ran out of ammunition, said M.V. Rao, police superintendent of the Aurangabad area in Bihar state, where the massacre took place.
Then the attackers stormed several homes and ordered the women, children and elders to stand in a line. They were shot and killed.
"We were sleeping, and suddenly the firing started," said Anupama Devi, 68, whose two daughters-in-law were killed in the attack. "I ran out and screamed, 'Why are you killing us?'"
Devi quoted one of the attackers as shouting: "Shut up, we have come to take revenge." Satyendra Singh, 23, whose brother was killed, said some of the attackers were injured and taken away by their comrades.
"This is the handiwork of the Ranvir Sena," Rao told The Associated Press, referring to the upper caste militia.
Altogether, a young girl, seven boys, 19 women and seven old menall members of lower casteswere killed in Miapur village in east India. Fifteen people were wounded.
Caste-related violence often flares in Bihar state between the Ranvir Sena and Maoist guerrillas belonging to the People's War Group and the Maoist Communist Center, who say they represent the underclass.
Revenge attacks are often carried out against villagers and scores die each year.
But analysts said hatred between different castes in the centuries-old social hierarchy of Hindus, who form nearly 83 percent of India's 1 billion people, was not the only reason for the seemingly unending cycle of killings.
"It is not a problem of caste or policing. It is a problem of infighting among the political bosses," said Shivendra Narayan, senior anthropologist at the independent A.N. Sinha Institute of Social Sciences in Patna.
Rival political parties in the state accuse each other of funding rival groups. Hundreds of unemployed youth in Bihar are sucked into the rivalry and end up joining the rival groups according to their caste affiliations, analysts say.
Maoist rebels in the state rode to strength along with the rise of a slew of political parties that represent the landless lower caste people. To fight their growing influence, powerful landowners started creating their own militias.
"The electoral empowerment of the lower castes has contributed to the violence," said Saibal Gupta of the Asian Development Research Institute. "For a person here, his caste is his only identity."
Though no one claimed responsibility for the massacre, eyewitnesses said the killers announced they were acting in retaliation for the killing of 11 upper caste villagers on Sunday.
Authorities have since rushed about 400 police to Miapur. Angry villagers refused to allow district officials to take away the bodies of the victims, saying they wanted Rabri Devi, the chief minister of Bihar, to come to Miapur.
The state's police chief said his men had sealed the borders of the district and were searching for the attackers.
Miapur, a village accessible only by foot, is 5 miles from Senari village, where 34 upper caste villagers were killed by the Maoist Communist Center last year.
By INDRANIL SINGH