Six persons, including four security personnel were killed by armed Maoists in separate incidents in Orissa, Bihar and West Bengal in fresh attacks today. <br/><br/>The Maoists blew up a government toll plaza in Gaya district in Bihar using dynamites and looted 16 weapons. Two persons including a security guard and a truck driver were killed in the attack.<br/> <br/>In Orissa, three security personnel were killed and six injured, four of them critically, in a fierce encounter with Maoists in Gajapati district early today. Acting on a tip-off about the movement of ultras, a team of security personnel including the elite anti-naxal Special Operation Group and state police launched a combing operation in Ambajari forest in the wee hours.<br/> <br/>In another incident in the nearby Malkangiri district, about 50 armed ultras blew up a pump house and control room near the pipeline of a private industrial house meant for movement of minerals. The ultras raided the area in the early hours and triggered the explosion after overpowering the guards.<br/> <br/>In West Bengal, Maoists killed a CPI(M) activist, after abducting him from home in West Midnapore district. His bullet-riddled body was recovered from the area today.<br/><br/>The violence occured as the Maoist' 48-hour bandh in seven states to protest against the Government's operations against Naxals drew to a close.