Officials say about two hundred Maoist rebels ringed a village in the eastern Jharkhand state before dawn Monday, and hauled people out of their homes before gunning them down.
Officials say the victims were members of a village defense committee. These committees consist of villagers armed and trained by security forces to defend against attacks by Maoist insurgents, who are active in that area.
Monday's attack is the biggest in the state targeting civilians. It comes nearly a week after 23 policemen and a civilian were killed in a neighboring state in a landmine explosion also blamed on Maoist rebels.
The Maoists say they are struggling to end the oppression of poor people by the government and rich landowners.
In recent weeks, several Maoist groups in India and communist rebels in Nepal fighting to topple the country's constitutional monarchy have said they will work together to promote communism.
A political analyst, Subhash Kashyap, at the independent Center for Policy Research in New Delhi, says the Maoists represent a growing threat all along the eastern coast of India and in Nepal.
"It is becoming a serious menace right from the extreme south, up to Nepal, there is almost a corridor consisting of Maoists or similar terrorists in different names and they seem to be now in close alliance with each other," said Mr. Kashyap. "Their game plan seems to be to destabilize the whole of South Asia."
In India, the rebels are mostly active in the poorer and underdeveloped regions of the country such as Bihar, Jharkhand and Andhra Pradesh. Mr. Kashyap urges authorities to tackle the guerrillas more effectively.
"Authorities have to tackle the problem both at the social and economic level as also at the law and order and military level. Much more needs to be done," he added. "The government has to be more alert to this problem than it has so far shown itself to be."
Authorities in different states have made efforts to hold a dialogue with the Maoists in the past, but so far there is little headway in controlling the guerrillas.