Maoist rebels have shot dead four policemen and wounded another four in the eastern Indian state of Bihar, police say.
A police spokesman quoting local eyewitnesses said the officers were killed just after midnight when up to 600 rebels attacked a police camp.
Police say the attack took place at Khaira village in Lakhisarai district.
They say that the rebels ordered the police to give up their arms but they refused to do so, and fought back.
Police said the rebels also blew up railway tracks at two places nearby.
The Maoists say they are fighting to defend the rights of the poor and indigenous tribes.
Maoists are active in several Indian states
Correspondents say that of Bihar's 38 districts, 18 are badly affected by the Maoist insurgency. Central Bihar in particular has a long bloody history of killings.
In November 2005, Maoist rebels raided a jail in Jehanabad district and freed more than 300 inmates.
The rebels are pressing for the creation of a communist state comprising tribal areas in the states of Andhra Pradesh, Maharashtra, Orissa, Bihar and Chhattisgarh.