The four were moving in Nudamarthi forests under Paderu division of the district in Andhra Pradesh when they were spotted by a police team which was on a combing operation.
When the team asked them to surrender, the ultras tried to escape, but were surrounded and captured, police said.
Those arrested were identified as T Deruka alias Venkata Rao, P Sanyasi Rao alias Sania, T Chanti alias Puttu and K Kameswara Rao.
The extremists had participated in several unlawful activities, including blasting of bridges and firing at police, they added.