Officials reacted with outrage Sunday to an audacious attack by about 200 suspected Maoist rebels who set off a roadside bomb and opened fire on a convoy carrying Indian ruling Congress party leaders and members in an eastern state, killing 28 people and wounding 24 others.
Prime Minister Manmohan Singh, accompanied by party President Sonia Gandhi, visited the injured in a hospital in the capital of Chhattisgarh state and said the government would take firm action against the perpetrators.
"We are devastated," said Gandhi, who denounced what she called a "dastardly attack" on the country's democratic values.
Rajnath Singh, president of opposition Hindu nationalist Bharatiya Janata Party, said the country should unite in its fight against the Maoist insurgency.
The convoy was attacked Saturday in a densely forested area about 215 miles (345 kilometers) south of Raipur, Chhattisgarh's capital, as the Congress members were returning from a party rally.
Four state party leaders and five police officers were among those killed. Other victims were party supporters.
Police identified one of those dead 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 included former federal minister Vidya Charan Shukla, 83, 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 R.K. 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.
K.P.S. Gill, a former police chief of Punjab state who has written widely on reform, said the attack was "a very horrifying incident."
However, Gill said the state government was incapable of devising a strategy to tackle the Maoist threat. "They don't have the political will and bureaucratic and police set-up to prevent such attacks," he said.
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 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.
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.
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.