Maoist rebels have attacked a security post in central India, killing 50 police officers, police say.
The Maoists launched a co-ordinated assault
The attack, one of the worst in decades of insurgency, happened in the rebel stronghold area of Dantewada, in Chhattisgarh state.
The Maoists, who have fought a 30-year insurgency, say they are fighting for the rights of landless farmers and neglected tribes.
Thousands have died in their campaigns in central and southern India.
The rebels attacked the security post - manned by 75 policemen - in Bijapur just before dawn on Thursday.
Under cover of darkness, they surrounded it.
The BBC's Damian Grammaticas in Delhi says that the insurgents opened fire in a co-ordinated assault, throwing hand grenades and home-made petrol bombs into the compound before storming it.
They seized a hoard of weapons from the post, 1,500km south of Delhi, then escaped into the jungle.
It is thought dozens of Indian policemen and soldiers were based at the post, along with many local militiamen.
The first security forces to arrive after the attack reported a large number of bodies scattered around the barracks but said they were unable to count them all because the rebels had planted land mines at the scene.
Chhattisgarh's police chief said that 12 security force members were injured and at least five rebels were killed.
Earlier this month, five security personnel died in a landmine explosion in Dantewada district.
The rebels have a strong presence in eight of 16 districts of Chhattisgarh state.
Much of the outpost was destoyed in the attack
The militants are known as Naxalites after the district where their Maoist-inspired movement was born in the late 1960s.
They have become so powerful in some districts they run their own parallel administrations and justice systems.
Until recently, Naxalites have operated in pockets of jungle in India's poorest states.
But correspondents say there is now more unity between the various groups, and that Thursday's attack will feed into anxiety that they pose a growing threat.
Analysts talk about the emergence of the Red Corridor, a great swathe of Maoist militancy which stretches all the way from the border with Nepal, south through India to the sea.
Around 6,000 Indians are thought to have died since the Naxalite uprising began.