A suicide bomber believed to be from Syria killed at least 10 people and wounded more than 15 in Istanbul’s historic center on Tuesday.

Senior security officials said the attack near the Blue Mosque and Hagia Sophia was probably planned by Islamic State.

President Tayyip Erdogan condemned the attack in Sultanahmet square saying a Syrian was thought responsible and that the blast would only harden Turkey’s resolve in fighting terrorism.

Deputy Prime Minister Numan Kurtulmus said the bomber had been identified from body parts found at the scene and was a Syrian national born in 1988. At the moment, authorities are investigating any links he might have with terrorist groups.

Sources in Prime Minister Ahmet Davutoglu’s office said most of the people killed were Germans.