At least six civilians were killed driving home from the shops when their vehicle struck an improvised bomb in eastern Afghanistan on Wednesday, an official said. They were heading home from a weekly shopping trip when the roadside bomb, widely seen in Taliban attacks on military targets, struck their vehicle, Mubarez Zadran, a spokesman for the provincial government told foreign news agency. The incident in Tani district, a troubled region in Khost province, is the latest in a string of Taliban-related violence taking its toll on Afghan civilians -- about 2,000 of whom are killed each year, the United Nations has said.