Twelve police officers have been killed by a landmine explosion in the eastern Indian state of Jharkhand, police say.
The officers were carrying out a patrol in a police vehicle through the Maoist rebel stronghold of Burudih, 160km (100 miles) south of the capital, Ranchi.
A police spokesman said the rebels had been planting mines in the area to deter attacks by the security forces.
More than 6,000 people have died during the Maoist rebels' 20-year fight for a communist state in parts of India.
Last week, at least nine people, including six policemen, were killed in clashes between security forces and Maoist rebels in Bihar state.
Prime Minister Manmohan Singh has said the Maoist insurgency is the "single biggest threat" to India's security.
The rebels, who operate in several Indian states, say they are fighting for the rights of poor peasants and landless workers.