Maoist rebels attacked a police convoy in Dumka district of Jharkhand, an eastern Indian state, on Tuesday, killing at least five policemen, television channels reported.
A senior police officer was among those killed, the reports said.
The Maoists, who say they are fighting for the rights of the poor and landless and want to overthrow the government, have stepped up attacks in recent months.
Last month, the rebels killed three people in an attack on a passenger train in Bihar. In May, Maoist rebels ambushed a convoy of Congress politicians in Chhattisgarh, killing at least 27 people.
The rebels, also known as Naxals, have fought for decades in a wide swathe of central and eastern India, including many resource-rich regions where tensions run high between poor farmers and industrial developers.
Prime Minister Manmohan Singh has described the Maoist insurgency as India’s biggest internal security challenge.