New Delhi (CNN) -- At least 24 people were killed and 33 were injured in Saturday's audacious Maoist attack on a political motorcade in India's Chhattisgarh state, the province's home secretary told CNN Sunday.
No arrests have been made so far, but investigations have begun, Chhattisgarh's Home Secretary N.K. Aswal said.
The assault on a convoy of politicians from the country's ruling Congress party also killed Mahendra Karma, founder of a controversial anti-Maoist tribal militia called Salwa Judam, or the Purification Hunt, authorities say.
At least 16 cars in the motorcade of local Congress leaders were passing through a forested area in the eastern Indian state when Maoists triggered a land mine and opened fire on them, area Police Superintendent Mayank Srivastava told CNN.
At least 200 guerrillas were involved in the ambush, Srivastava said, citing witness accounts.
Among the dead were eight policemen, three laborers and some car drivers, he added.
On Sunday, Indian Prime Minister Manmohan Singh visited some of the injured in a hospital in Raipur, the capital of Chhattisgarh state. He was accompanied by his 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.
Saturday's Maoist raid 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 liberation struggle.
Since the 1960s, the militants have said they are fighting for the dispossessed.
Authorities suspect that Maoists enjoy support not only in the poorest areas and in tribal communities but also among youth and intellectuals.
In addition to targeting police, alleged police informers and people they call "class enemies," the insurgents also are believed to be attacking infrastructure such as roads, bridges, railways, and power and telecommunication networks.