An award-winning Japanese journalist died Tuesday from wounds sustained in Aleppo, a Syrian activist group said in a statement. Identified by the Japanese embassy in Turkey, journalist Mika Yamamoto worked for Tokyo-based independent news wire Japan Press and had covered conflicts in Afghanistan and Iraq. Japan Press was not immediately available for comment. According to the Syrian Observatory for Human Rights, a Lebanese journalist, a Turkish journalist and an Arab journalist also disappeared in Aleppo, but these claims have not been verified. At least 18,000 people have been killed in Syria since the uprising against President Bashar al-Assad began 17 months ago. According to the United Nations, 170,000 civilians have fled the country, while 2.5 million people have remained in Syria and are in need of aid.