Kabul: Suspected Taliban gunmen stopped two vehicles in central Afghanistan and shot dead 15 passengers at the side of the road, officials said on Friday, in the latest attack to highlight the growing civilian toll from violence. Only one man escaped after the gunmen held up two vehicles on a road in Ghor province and shot dead 11 men, three women and one child. "Armed gunmen stopped two vehicles and shot dead the passengers," Abdul Hai Khatibi, spokesman for the governor of Ghor province, told a news agency. "They ordered all passengers to stand in one line, and then they shot them dead one by one. "One man managed to flee. All of the others were shot in the head and chest." Fahim Qaiem, Ghor provincial police chief, confirmed the incident to a news agency and blamed suspected Taliban militants for the killings late on Thursday. The attack occurred the same day that two Finnish female aid workers were shot dead by unidentified gunmen while in a taxi in the western city of Herat. Afghan politics is mired in a bitter election dispute between poll rivals Ashraf Ghani and Abdullah Abdullah that threatens to trigger instability and revive ethnic tensions that ravaged the country during the 1992-1996 civil war. NATO combat troops will withdraw from the country by December, and reports suggest unrest is already worsening nationwide. According to recent UN figures, civilian casualties soared by 24 percent in the first half of 2014, while the International Crisis Group has said the "overall trend is one of escalating violence and insurgent attacks".