Fourteen or more alleged Maoists, including a woman, were killed early this morning in a ''fierce encounter'' with police in Odisha's Malkangiri district, state police officials said.
This is the biggest single blow to the Naxalites (far-Left insurgents) in the state, the officials said.
The gun battle took place in a forest close to the border with Chhattisgarh, and lasted several minutes.
The Maoists who were killed are suspected to have been involved in the attack on a convoy of Congress leaders in Chhattisgarh in May this year, the police said.
The operation against the insurgents was carried out jointly by a team of the Special Operations Group (SOG) and the District Voluntary Force (DVF), which raided a Naxalite camp, and ''retaliated'' when the extremists fired at them.
"Fourteen Maoists were killed. Arms were also seized," Inspector General of Police Soumendra Priyadarshi said.
Superintendent of Police for the Malkangiri district Akhileswar Singh, who led the operation, said some explosive material, arms and ammunition were seized from the site, and (for good measure) Maoist literature.
Describing the operation as a major success in the drive against left-wing extremists in the region, Deputy Inspector General of Police Devdutt Singh said a massive search operation has been launched in the forest after the encounter.
Malkangiri, some 650 km from the state capital of Bhubaneswar, is a known Maoist stronghold.
The Maoist problem has been described by Prime Minister Manmohan Singh as ''the biggest threat'' that India faces. On 27 August this year, the insurgents killed four Border Security Force (BSF) personnel in a landmine blast in Koraput district.
Whether there is any link between Saturday's police encounter and Koraput attack by Maoists is unclear so far.
Earlier, on 23 August 2013, Maoist leader Madhav alias Golla Ramullu, who carried a Rs4 lakh reward on his head, was killed in an encounter with security forces in Odisha's Malkangiri district.
Madhav was allegedly involved in many incidents of murder, including the killing of 38 security personnel in Chitrakonda reservoir, as well as extortion and planting land-mines.