Six policemen were killed and seven injured in a landmine blast at Barkathal in West Tripura district, about 25 km from Agartala, on Monday, police said.
Suspected All Tripura Tiger Force insurgents had planted the landmine which exploded at about 1130 IST when a team from the Sidhai police station was on its way to the Barkathal marketplace on routine duty.
The dead included three special police officers and an assistant sub-inspector.
The seven injured policemen have been admitted to a hospital. The condition of two of the injured is stated to be critical.
Top police officials from Agartala have rushed to the spot.
The All Tripura Tiger Force and the National Liberation Front of Tripura have asked people to boycott Independence Day celebrations.