At least seven Maoists and five Central Reserve Police Force personnel have been killed in one of the biggest encounters in recent times.
The toll is likely to mount, as more details were yet to emerge.
One of the slain personnel has been identified as CRPF commandant Manoranjan Singh.
According to the police sources in Raipur, the encounter that started on Friday morning near Palachamela village of Chhattisgarh's Dantewada district, close to the border with Andhra Pradesh, was still going on.
Five CRPF jawans are reportedly missing.
The fierce encounter began when Maoist ambushed a big CRPF contingent, which was returning to their base campus at Kunta after a successful raid against the Maoists in the forest area.
During the search operation over the last two days, the force unearthed and destroyed an arms manufacturing unit of the Maoists.