Maoists have blown-up a bus killing at least 50 persons, including several Special Police Officers, in Dantewada district of Chhattisgarh. <br/><br/>The Naxals attacked the bus carrying passengers from Gadiras to Bhusaras in Dantewada district, nearly 400 Kilometers from Raipur, using Improvised Explosive Device this afternoon. <br/><br/>Official sources said, the SPOs, who are civilians assisting police in fighting the Naxals, were attached to Dantewada police. <br/><br/>The attack came a day before the Maoists' call for a 48-hour bandh in five states, including Chhattisgarh, from today in protest against the security operations launched against them by the Centre. <br/><br/>A high alert has been sounded in Chhattisgarh following yesterday's Naxal attack. <br/><br/>While some dead bodies have been recovered yesterday, police parties have been rushed to the spot this morning to recover the remaining bodies. <br/><br/>Those who were injured in the incident have been admitted to local hospitals in Jagdalpur and Dantewada. <br/>