In Orissa, armed Maoists attacked a hydel power unit at Ballimela in Malkangiri district, paralysing energy generation at the plant.<br/><br/>Over 20 heavily armed ultras attacked the unit run by<br/><br/>Orissa Hydro Power Corporation (OHPC), about 60 km from here, set afire some portions of the plant and overpowered those on duty last night, Superintendent of Police Satyabrata Bhoi said.<br/><br/>After tying about six persons to a structure outside the power house, the Maoists ransacked the valve house atop a hill and set fire to equipment, causing extensive damage to some machines.<br/><br/>The red rebels put up several posters and banners carrying messages against the government and police before disappearing into the nearby dense forest.<br/><br/>Local residents said that the Maoists triggered explosions damaging machines and some vital structures in the power house.<br/><br/>Meanwhile, additional security forces were rushed to the site and a massive combing operation was launched to track the ultras, they said.<br/><br/>Senior engineers and experts have rushed to the plant to take steps for resumption of power generation, official sources said, adding that the project with a total capacity of 510 mw, was generating about 360 mw at present in view of low water level.<br/><br/>