The attack on a convoy of Congress Party politicians in Bastar district also injured 32 people, The Times of India reported.
However, Indian Defense Minister A.K. Antony said 2,000 additional paramilitary force personnel had been sent to Chhattisgarh.
The deployment followed a request from the state government for more military help to provide security for political leaders as well as engage in anti-Maoist operations, the Times of India report said.
Around 30,000 paramilitary personnel already operate in Chhattisgarh, one several states in Eastern India in which Maoists -- also called Naxalites -- operate.
More than 1,900 people -- including 570 civilians and 700 security personnel -- have been killed in Chhattisgarh, one of the worst-affected states, in the past eight years.
In the latest attack, 100-150 Maoists ambushed the group's vehicles along a heavily forested road late in the afternoon as the politicians were returning from a political rally, a report by The Indian Express newspaper said.
The insurgents felled trees across the road and triggered a land mine before starting a gun battle, police sources said. The group's security officers returned fire but ran out of ammunition.
One survivor said nearly 20 vehicles in the convoy came under attack and insurgents methodically went around checking almost every vehicle after the fighting had ended.
Local residents and journalists who reached the scene led survivors to a nearby police station and a hospital. Security forces couldn't reach the spot until 9 p.m., a report by the Hindustan Times said.
Chhattisgarh Congress leader Nand Kumar Patel and his son Dinesh, who were kidnapped by the militants during the Saturday attack, were found dead Sunday along with the bodies of eight others.
Indian Prime Minister Manmohan Singh condemned what he called the "dastardly" Maoists attack on the Congress party leaders and workers.
The National Investigation Agency has launched an investigation into the incident.
Chhattisgarh is one of the states in what the government calls the Red Corridor because of the insurgency. Other states in the Red Corridor are West Bengal, Jharkhand, Bihar, Orissa and northern parts of Andhra Pradesh.
A surge in deaths to more than 1,100 in 2009 prompted the government to launch Operation Green Hunt, an ongoing military offensive by 50,000 paramilitary soldiers working with regular police forces.
Maoists are often called Naxalites after the village of Naxalbari in West Bengal state where they for formed in the late 1960s.
Naxalites demand the rural poor receive more of the wealth from exploiting natural resources, especially large mining projects.
Maoists also put pressure on local people -- sometimes using brutal methods including kidnapping -- to persuade them not to work on government infrastructure projects.
Last month police said at least 10 rebel Maoists were killed during a clash in a remote area of eastern Chhattisgarh. Security forces also claimed they injured a large number of rebels and recovered arms and ammunition.
In one of the more brutal attacks, Maoists derailed a train in Chhattisgarh in 2010, killing more than 150 people.