A suspected member of the Islamic State (IS) group has killed 10 people, at least nine of them German tourists, in a suicide bomb attack in the Turkish city of Istanbul, officials say. They say the Syrian national carried out the attack in the Sultanahmet district, near the famous Blue Mosque. Fifteen people were wounded, many of them also German. President Recep Tayyip Erdogan said Turkey was the "top target for all terrorist groups in the region". His country, he added, was "fighting against all of them equally".