At least 12 Central Reserve Police Force jawans were killed on Monday in an ambush by suspected naxalites in Bijapur district of Chhattisgarh.
One of the attackers was also killed in the exchange of fire that followed, according to CRPF officers in New Delhi.
Jawans belonging to the 170 Battalion of the force who were on duty were fired upon by the ultras and the resulting skirmish left at least 12 personnel dead, they said.
The troops, deployed in the area to provide security to Border Roads Organisation personnel, retaliated by opening fire, killing one of the ultras.
The attack took place at around 1330 hours between Modukpal and Kongupalli in Bijapur district.
The CRPF, which has cordoned off the area, have launched a counter-offensive to flush out the naxals who are suspected to be hiding in the vicinity.