About 200 suspected Maoist rebels have set off a land mine and opened fire on a convoy of cars carrying local leaders and supporters of India's ruling Congress party in an eastern state, killing 28 people and wounding 24 others in one of their most audacious attacks on politicians.
Senior police officer M Gupta said the ambush occurred on Saturday in the Sukma area, about 215 miles (346km) south of Raipur, the capital of Chhattisgarh state.
The convoy was attacked in a densely forested area as the Congress members were returning to the state capital after attending a party rally, said Ram Niwas, a state police official. Four state party leaders and five police officers were among those killed. Other victims were party supporters.
"We are devastated," said Congress party President Sonia Gandhi, who denounced what she called a "dastardly attack" on the country's democratic values. Prime Minister Manmohan Singh said the government would take firm action against the perpetrators.
Police identified one of those killed as Mahendra Karma, a Congress leader in Chhattisgarh who founded a local militia, the Salwa Judum, to combat the Maoist rebels. The anti-rebel militia had to be reined in after it was accused of atrocities against tribals - indigenous people at the bottom of India's rigid social ladder.
The dead also included state Congress party chief Nand Kumar Patel and his son. The injured, who included former federal minister Vidya Charan Shukla, 83, were taken to hospital, police said. The Press Trust of India news agency said the attackers blocked the road by felling trees, forcing the convoy to halt. Police officer RK Vij said the suspected rebels triggered a land mine that blew up one of the cars. The attackers then fired at the Congress party leaders and their supporters before fleeing.
The Congress party is the main opposition party in the state. It has stepped up political activities, trying to win the support of tribals, ahead of state elections scheduled to be held by December.
Maoist rebels carried out two major attacks in Chhattisgarh in 2010. They ambushed a paramilitary patrol in April that year, killing 76 troops in their worst attack ever. A month later, they triggered a land mine under a bus carrying civilians and police, killing 31.
The rebels, known as Naxalites, have been fighting the central government for more than four decades, demanding land and jobs for tenant farmers and the poor. They take their name from the West Bengal village of Naxalbari where the movement began in 1967. The fighters were inspired by Chinese Communist revolutionary leader Mao Zedong and have drawn support from displaced tribal populations opposed to corporate exploitation and official corruption.
Prime Minister Singh has called the rebels India's biggest internal security threat. They are now present in 20 of India's 28 states and have thousands of fighters, according to the Home Ministry. The government has offered to begin peace talks with the rebels, but without success. The Maoists demand that it first withdraw thousands of paramilitary soldiers deployed to fight the rebels.