"We suspect killing of some Maoists during the encounter. However, police are yet to get the bodies of the slain rebels," Malkangiri superintendent of police Mitrabhanu Mohapatra said.
"There was no casualty on the police side. I can tell the number of Maoist casualties only after the encounter is over and the bodies are recovered. The operation is still on," IG, South West, Yashwant Jethwa said.
There were about 60 ultras at the Maoist camp at Pingapuram village, he added.
A heavy exchange of fire took place between the security personnel and armed left wing extremists and it is continuing since last evening at the cut off on other side of Balimela reservoir in Malkangiri district.
The encounter took place after security personnel launched a regular combing operation in the cut off area last evening following intelligence reports that Maoists from neighbouring Andhra Pradesh and Chhattishgarh had assembled in the cut off area.