A journalist working for the private NDTV television station said land disputes and caste issues were also likely behind the attack.
The provincial government has sent two Special Task Force units to investigate, though acces to the remote area is difficult.
Bihar has seen a number of deadly Maoist attacks in the last couple of months.
On August 23, five policemen were killed and two others injured in an attack in Sono Bazar area of Bihar's Jamui district.
In the first half of 2009, 56 Maoist attacks have been reported.
The Maoists in India are also known as Naxals, given that the first armed uprising took place in a small village called Naxalbari in the neighbouring state of West Bengal some 40 years ago.