People in Afghanistan have gone to the polls to vote for a new president to replace Hamid Karzai after 13 years of being in power.The presidential election began on Saturday, with Afghans going to more than 600 polling stations set up across the country to choose among eight candidates running for presidency. According to Interior Minister Omar Daudzai, all of Afghanistan’s 400,000 troops are on duty across the country in order to prevent attacks on polling stations and voters by Taliban militants. The militants have rejected the election, saying it is a plot by foreign powers. They have threatened to attack polling staff, voters, and security forces. Officials say the capital, Kabul, has been closed off from the rest of the country by checkpoints and roadblocks.Kandahar was also blocked off ahead of the election, with authorities advising residents to stay home.On April 4, two female Associated Press journalists were shot in eastern Afghanistan. Anja Niedringhaus, 48, was killed and the second victim was injured. Opinion polls show that former Afghan foreign ministers, Abdullah Abdullah and Zalmai Rassoul, and former finance minister, Ashraf Ghani Ahmadzai, are the frontrunners. Karzai, who has ruled since the Taliban were removed from power after the US-led invasion of Afghanistan in 2001, was not allowed to run for a third term as president by the constitution.