Ten people, including eight German tourists, were killed in a suicide bombing in Istanbul carried out by a man suspected of being linked to IS.
Turkish media reports say the bomber was a Syrian citizen but had been born in Saudi Arabia.
The explosion struck in the heart of the tourist district Sultanahmet, near the famous Blue Mosque.
A witness says there was confusion immediately after the blast.
"There was an explosion and we were all afraid, we were trying to cover ourselves. After the first shot we checked the square and there was people lying on the ground..."
Many of those killed and wounded were German tourists.
German Chancellor Angela Merkel says she is saddened to think those who had travelled to Istanbul would not make it home
"I'd like to say to the families of the victims - you are not alone. We stand with you, with a lot of strength, We also wish to the wounded that they recover very quickly."
Turkish President Recep Tayyip Erdogan has condemned the attack.
"I strongly condemn this attack - this apparent terrorist act caused by a suicide bomber. I'd like to offer my condolences to those who lost their loved ones and pray for those who lost their lives. Once again this shows us how important it is to be united in the face of terrorism. Turkey's determined resolute stance against terrorism will continue."
While there is as yet no claim of responsibility for this attack, the Turkish government has made it clear it's working on the assumption the attacker is an IS sympathiser, at the very least.
Turkish Prime Minister Ahmet DavutoÄlu says those responsible will be punished.
"I call on all humanity. We need to stand in global solidarity. We need to stand shoulder-to-shoulder in the face of Istanbul and Ankara attacks like we did in the attacks in Paris."
Turkey had two bombings last year blamed on IS: one in the town of Suruc near the Syrian border, and another in the capital Ankara, the latter killing more than 100 people.
Last year Turkey agreed to take a more active role in the United States-led campaign against IS, carrying out air strikes in Syria.
It also allowed US warplanes to strike IS targets from its base in Incirlik and moved to tighten security along its border with Syria.
