nagpur, Aug. 28 -- At least four Maoists were killed during an encounter with security forces in Koparshi forest area of Gadchiroli district in Maharashtra on Wednesday morning, officials aware of the details said. The incident took place near the border area of Gadchiroli and Narayanpur district of Chhattisgarh during a search operation, which was launched after police received security forces received a tip-off about the presence of Maoists in the area on August 25. The search party comprised of 19 units of the C-60 commandos, an elite anti-Maoist squad led by additional superintendent of police M Ramesh. Gadchiroli superintendent of police Neelotpal said that Wednesday's encounter began after the Maoists opened fire on the commandos, prompting a strong retaliation from the forces. During the eight-hour long encounter, four Maoists were killed. Forces also recovered a significant cache of arms and ammunition from the site, he said. "The area has been cordoned off, and a large-scale search operation is currently underway to flush out any remaining ultra-left activists," the SP said. Thirty Maoists carrying a combined bounty of Rs.81 lakh, including a sub-division bureau incharge and several company and area committee members, surrendered before police in Bijapur district of Chattisgarh on Wednesday, officials said. The surrendered cadres include KK sub-division bureau incharge Sonu Hemla alias Koroti. The others are members of Company Number 2, platoon party members, area committee cadres, PLGA fighters, CNM and DAKMS workers....