At least six Indian policemen have been killed in an attack by suspected Maoist rebels in the southern state of Karnataka, officials said.
The rebels say they are being targeted by the police
Five policemen were injured in the attack in a village bordering neighbouring Andhra Pradesh, where the rebels have been active for many years.
The rebels withdrew from peace talks with the Andhra Pradesh government last month after clashes with the police.
They have been fighting since 1980 for the creation of a communist state.
The chief of Karnataka police SN Borkar told the BBC that the rebels blew up the school building where the policemen were sleeping at a village in Pavagada, 130km from Karnataka's capital, Bangalore.
The policemen had returned from a routine patrol in the border area, he said.
"There was an armed guard but it appears that the gang stealthily planted explosives. They also used grenades in the attack," Mr Borikar said.
The attack came five days after a top Maoist leader, Saket Rajan, was killed in what the police described as an "encounter" in Karnataka.
The chief minister of Karnataka Dharam Singh has ordered an investigation into Rajan's killing after human rights activists charged the police with faking the "encounter".
A number of Maoist guerrillas were killed by the police in neighbouring Andhra Pradesh after the peace talks broke down.
Until October last year, the rebels were known as the People's War Group. But at that time they announced a merger with the Maoist Communist Centre to become the CPI (Maoist).
The rebels have been fighting since 1980 for the creation of a communist state comprising tribal areas in the states of Andhra Pradesh, Maharashtra, Orissa, Bihar and Chhattisgarh.
The BBC's Habib Beary says that some rebels have been moving to the border areas of Karnataka after the police cracked down on them in Andhra Pradesh.