Updated

Authorities say a roadside bomb has killed four civilians in southern Afghanistan.

Omar Zwak, the spokesman for the governor of southern Helmand province, says the blast Wednesday struck civilians traveling by car.

Civilians increasingly find themselves under fire as the 2001 U.S.-led war draws to a close, as Afghan forces take the lead in operations targeting the Taliban.

The United Nations reported in July that the civilian death toll in the war in Afghanistan rose 17 percent for the first half of this year. The U.N. said 1,564 civilians were killed from January through June, compared with 1,342 in the first six months of 2013.

The U.N. found that Taliban fighters and other militants have been responsible for the majority of the civilian killings, some 74 percent.