At least three Indian security forces personnel were killed and one more injured in a landmine blast triggered by suspected Naxalites in the central state of Chhattisgarh on Tuesday, a senior police official said. "The landmine blast happened in the state's Sukma district when a contingent of para-military Border Security Force personnel was passing through a Naxalite-infested village. While three personnel were killed on the spot, one injured has been admitted to a local hospital," he said, on condition of anonymity. A massive manhunt has been launched to track down those responsible for the blast, the official added. The Border Security Forces are part of central Indian forces deployed in the state in the wake of the ongoing assembly polls which began Monday and registered a record voter turnout of 67 percent on the first day, despite Naxalite threats. Naxalites are active in Chhattisgarh and some months back they had wiped out the entire top brass of the country's ruling and the state's opposition Congress party while the leaders were returning from an election rally.