NEW DELHI, India (CNN) -- Six police officers were killed in a landmine explosion triggered by suspected Maoists in eastern India, authorities said Monday.
Three others were injured in the attack in Dantewada district in Chhattisgarh state, said Pawan Deo, a state police official.
The officers were returning from duty Sunday when the landmine blew up their van, he said.
Maoists -- known as the Naxalites -- have launched a series of attacks throughout the country. The rebels say they are fighting for the rights of the poor and the dispossessed who have not benefited from the state's resources.
Indian Prime Minister Manmohan Singh has called the rebels India's biggest security threat.