At least 12 people including poll officials and paramilitary soldiers were killed in separate attacks by suspected Maoist rebels on Saturday during India's staggered elections, according to dpa. Both attacks took place in the central state of Chhattisgarh that has been wracked by the left-wing insurgency. Voting in the fourth phase of the elections was underway in far-off states of Assam, Goa, Sikkim and Tripura when the attacks took place. In the first attack in the Bijapur district, at least six officials on polling duty were killed after the insurgents blew up their bus with a landmine, senior police official Dipanshu Kabra said. "The officials were returning from remote areas after duties for the polling in the region two days ago," he said. Five more people were injured in the explosion. In a similiar strike on an ambulance in the Jagdalpur district, five men from the Central Reserve Police Force and the driver were killed and four more injured, other officials said. Saturday's attacks were the deadliest strikes by the insurgents since India's polls opened on April 7 and a total of 19 people, most of them security men, have been killed so far. India's elections are taking place under threat from the Maoist rebels who are carrying out attacks to disrupt the polls. The elections continue until May 12 and results are due on May 16. The incumbent Congress party and main opposition Bharatiya Janata Party are the main contenders, each with alliances of smaller and regional parties.