Ten aid workers have gone missing in civil war-torn South Sudan, the United Nations said Thursday. Three UN staffers and seven aid workers, all of them South Sudanese, went missing early Wednesday when their convoy driving from Yei town to Tore in Central Equatoria disappeared, AP reported, citing the statement. The aid workers are with South Sudanese Development Organization, ACROSS, Plan International and Action Africa Help. This is the third time aid workers have been held by armed groups in the last six months alone. Two other local aid workers were killed earlier this month.