The Maoists are active in several Indian states
Ten policemen have been killed in an attack by Maoist rebels in the eastern Indian state of Bihar, officials say.
The incident took place in Nawada district, when more than 200 rebels attacked security forces deployed at a religious function.
Three others were injured. The rebels took away a number of police weapons.
The rebels are active in nearly half of Bihar's districts. More than 1,000 people have died in 15 years of Maoist-related violence in the state.
Officials say police fired in retaliation following the latest attack in Nawada late on Monday. But it is not yet known whether the rebels suffered any casualties.
Last year, 64 local politicians resigned in Bihar following threats from the rebels.
Some of the politicians were abducted by the rebels for several days in protest against alleged police abuses.
Thousands have died in Maoist campaigns across central and southern India in the past 30 years
The Maoists say they are fighting for more rights for indigenous people in at least five states, including Bihar, which has a reputation as India's most lawless state.
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.