Afghanistan kicked off a presidential election campaign Sunday amid security concerns, as two aides of one candidate were killed in the western region, dpa reported. Eleven candidates are in the fray for the April 5 election. Incumbent president Hamid Karzai is not eligible to run for the third term. The candidates include Abdullah Abdullah, who lost to Karzai in 2009; World Bank technocrat Ashraf Ghani; former foreign minister Zalmai Rassoul; jihadi strongman Abdul Rab Rassoul Sayyaf; and the president's elder brother, Qayyum Karzai. The two months of campaigning is expected to bring an increase in violence, Western military officials say. The Taliban have announced they plan to target officials as well as candidates and campaigners. The election comes at a time when the the NATO-led allied forces are set to leave the country after nearly 13 years.