At least 26 policemen have been killed in a landmine attack in eastern India, officials say.
The police were on patrol in a remote part of Jharkhand state, about 150 km (95 miles) from its capital Ranchi.
They suspect the attack was carried out by rebels of the banned People's War Group, who have been fighting for 20 years for a communist state.
Deputy Prime Minister LK Advani is due in Jharkhand on Thursday as part of a nationwide election campaign tour.
Police said the blast happened late on Wednesday when officers were searching for left-wing rebels in a dense forest area in Jharkhand's Chaibasa district.
Reports say their vehicle hit a landmine and was destroyed.
A police superintendent leading the team was seriously injured.
The People's War Group is an armed peasant movement that advocates revolution in the Indian countryside.
The rebels have been accused of targeting wealthy land-owners and security forces in Bihar.
A similar attack in the same area last year left 33 people dead.
In February, the People's War Group and another rebel group, the Maoist Communist Centre, said they planned to step up attacks against the police.
More than 6,000 people have died during the rebels' 20-year armed struggle for a communist state in tribal areas of India.