Four Border Security Force personnel were killed on Tuesday and two injured when Naxals blew up their vehicle, in a blast triggered by an improvised explosive device, in Odisha's Koraput district.
According to security sources, a convoy of three BSF vehicles carrying 18 personnel was ambushed when it was crossing Patangi and Sunki areas in the district.
The troops were moving from Malkangiri in the state to Vishakhapatnam in Andhra Pradesh when the incident occurred at around 9.30 am, during an official movement.
The IED, embedded in the road, exploded as the first vehicle crossed the route, leaving a subordinate officer and three jawans dead.
A large group of Maoists then began firing on the personnel who retaliated.
"The troops retaliated and firing was going on for an hour. All the weapons of the ambushed party are intact," a senior BSF officer said.
The two injured personnel have been rushed to the nearby hospital in Sunki while the gunfight has stopped, the officer said.
Additional reinforcements from state police and paramilitary have reached the spot and combing operations have begun.