At least two policemen have been killed and 10 others injured in a landmine explosion in central Indian state of Chhattisgarh, officials say.
The explosion took place as a vehicle carrying security personnel reached Kolar-ghat in Rajnandgaon, some 110km (70 miles) from state capital, Raipur.
Local police chief Vivekanand said the mines were planted by Maoist rebels.
Thousands have died in Maoist campaigns across central and southern India in the past 30 years.
The Maoists have a strong presence in eight of 16 districts of Chhattisgarh state.
Spike in violence
The rebels are pressing for the creation of a communist state comprising tribal areas in the states of Andhra Pradesh, Maharashtra, Orissa, Bihar and Chhattisgarh.
Rebel attacks on civilians have increased recent months and police say the rebels have also been targeting other state-owned installations.
The police say the rebels have killed at least 24 people this month in different incidents.
There has been no comment from the rebels regarding their involvement.
Maoists want communist rule across a number of states
Earlier this month, at least six people were killed and 33 injured in two attacks by the rebels in Bansaguda village in Dantewara district.
The rebels launched attacks on people who they suspected of being police informers.
The rebels also blew up a railway engine in an attack at Bhamri in Chhattisgarh's Dantewada district.
In February, 25 people were killed after Maoist rebels blew up two trucks carrying civilians.
Villagers in rebel-affected areas in the state have begun moving to government-run camps for safe shelter.
The government set up the camps after the authorities launched an operation against the rebels whom they accuse of killing and kidnapping villagers.
The government says there are more than 45,000 people, mostly tribes people, living in the camps.
The Indian government believes that there may be 10,000 armed Maoist rebels in India, correspondents say.