At least 17 security personnel and two Maoists were killed in the ongoing gun battle, which started on Monday at Karmatiya forest in Jharkhand's Latehar district.
Around 300 CRPF and Jharkhand Jaguar jawans went deep into the Karmatiya jungles, about 250 km from Ranchi as part of a combing operation when Maoists started indiscriminate firing from tree tops and hills.
Kranti Kumar, superintendent of police, said two soldiers were still missing.
Acting on a tip-off that a large number of Maoists had assembled in the jungle, four companies of Central Reserve Police Force rushed to the spot to nab them. But they were ambushed on the way.
"We received information that nearly 250 Maoist cadres, including some senior members, have assembled there. We went to catch them. But Maoist got wind of our campaign. They ambushed us. A fierce gun battle took place," Kumar said.
The ultras blew up bodies of two security personnel by blasting landmine. In that blast three civilians were also wounded.
"Maoist blew up bodies of two security personnel, in an inhuman way, by blasting landmine. In that blast three civilians were also wounded and one of them is seriously injured," added Kumar.
The injured soldiers were admitted to a local hospital in Daltonganj.
The guerrilla war, waged mostly from the forests of central and eastern India now poses the biggest internal security challenge, say analysts.
Hundreds of people have been killed and injured in the violence, perpetrated by the rebels as well as security forces in counter insurgency operations.