Polling for the first assembly elections in Chhattisgarh began on Monday under unprecedented security. An estimated 1.35 crore voters are likely to exercise their franchise to choose 90 representatives from 819 candidates.A tight security cover was thrown across the tribal state in view of heightened Naxal activities in the past few days.Naxalites set off a landmine blast killing six policemen and a civilian two days before the balloting in Bastar region.Out of 15,671 polling stations in the state, 3,399 have been marked sensitive and 1,580 hyper-sensitive.