New Delhi (CNN) -- A senior official from India's governing Congress party suffered brutal treatment at the hands of Maoist insurgents during an audacious and deadly attack on a political motorcade over the weekend, police said Monday.
The assault Saturday by hundreds guerrillas on the convoy of Congress politicians in a forested area of the eastern state of Chhattisgarh killed at least 24 people and wounded 33, according to authorities.
Among the dead was Mahendra Karma, a top local party leader and the founder of a controversial anti-Maoist militia named Salwa Judam, or the Purification Hunt.
His stance against the insurgents appears to have prompted them to take a vicious approach when they captured him.
They fired 30 to 40 bullets into Karma's body and smashed his head with the butt of their guns after killing him, said Ram Niwas, the state police chief.
"He was beaten brutally even after his death," he said.
Niwas said as many as 500 insurgents had participated in the attack. Police had previously estimated that around 200 attackers had raided the convoy.
At least 16 cars in the motorcade of local Congress leaders were passing through the area when the insurgents set off a land mine and opened fire on them, police said. Among the dead were eight policemen, three laborers and some car drivers.
Searching for suspects
Authorities haven't reported any arrests so far, but investigations are under way. Security forces are combing the area where the raid took place, Niwas said Monday.
A judicial inquiry has been ordered into Saturday's assault.
If any failings on the part of the police are found, "appropriate action will be taken," Niwas said when asked about his response to criticism of security in the area.
On Sunday, Indian Prime Minister Manmohan Singh visited a hospital in Raipur, the capital of Chhattisgarh, where some of those wounded in the attack were being treated. He was accompanied by the Congress party chief, Sonia Gandhi.
"We will pursue the perpetrators of this crime with urgency, and I can assure the nation that the government is committed to bringing them to justice," Singh said.
India's internal threat
Saturday's severe attack came barely three days after Singh announced what he called a significant decline in killings by left-wing insurgents, whom the federal government describes as the nation's gravest internal security threat.
"The quantum of violence as well as the resultant killings perpetrated by the left-wing extremist groups in 2012 declined significantly for the second successive year," said a report Singh released on Wednesday to mark the fourth anniversary of his second term in office.
He insisted his government has continued to provide public infrastructure and services in tribal districts hit by Maoist extremism.
The rebels, officials say, aim to seize power through an armed struggle. Since the 1960s, the militants have said they are fighting for the dispossessed.
Authorities suspect that the Maoists enjoy support not only in the poorest areas and in tribal communities but also among young people and intellectuals.
In addition to targeting police, alleged police informers and people they call "class enemies," the insurgents also are believed to have attacked infrastructure such as roads, bridges, railways, and power and telecommunication networks.