Turkish authorities say at least 10 people have been killed in an explosion in the center of Istanbul. The Istanbul governor's office said 15 other people were wounded in the blast, which occurred on January 12 in Sultanahmet district, a major tourist attraction. Turkish President Tayyip Erdogan says a person of Syrian origin is thought to have been responsible for the blast. The Sultanahmet neighborhood is Istanbul's main sightseeing area and includes the Topkapi Palace, Hagia Sophia, and the Blue Mosque.