Gunmen in Pakistan have shot dead an American aid worker and his driver in the north-western city of Peshawar. The men were killed just outside their office in the University Town area. It is not clear who the attackers were. Violence has surged in the north-west in recent months with a wave of attacks blamed on Islamist militants. A number of missile strikes inside Pakistan's tribal areas by US troops based in neighboring Afghanistan have fueled anti-American sentiment. (BBC)