Istanbul: A suicide bomber thought to be from Syria killed at least 10 people, at least nine of them German tourists, in Istanbul's historic heart on Tuesday, an attack senior security officials said was probably planned by IS militant group.
President Tayyip Erdogan condemned the bombing in Sultanahmet square, near the Blue Mosque and Hagia Sophia, major tourist sites in the centre of one of the world's most visited cities. He said 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 at the scene, and was a Syrian national born in 1988 whose links were being investigated.
At least nine of the people killed were German citizens, a senior Turkish government official said.
Sources in Turkish Prime Minister Ahmet Davutoglu's office earlier told Reuters that most of those killed were Germans and that Davutoglu had spoken by phone with Chancellor Angela Merkel to express condolences.
Merkel earlier said she was very worried Germans might be among the victims.
Several bodies lay on the ground in the square, also known as the Hippodrome of Constantinople, in the immediate aftermath. It was not densely packed at the time of the explosion, according to a police officer working there, but small groups of tourists had been wandering around.
"This incident has once again shown that as a nation we should act as one heart, one body in the fight against terror. Turkey's determined and principled stance in the fight against terrorism will continue to the end," Erdogan told a lunch for Turkish ambassadors, in a speech broadcast live on television.
Norway's foreign ministry said one Norwegian man was injured and was being treated in hospital. The Dogan news agency said nine Germans and one Peruvian were also wounded.
Two senior security officials told Reuters there was a high probability that Islamic State militants were responsible.
Turkey, a NATO member and candidate for accession to the European Union, is part of a US-led coalition against IS militants who have seized territory in neighbouring Syria and Iraq, some of it directly abutting Turkey.
There was no immediate claim of responsibility but hardliners, leftist and Kurdish militants, who are battling Ankara in southeast Turkey, have all carried out attacks in the past.
The Istanbul governor's office said the authorities were investigating the type of explosive used and who might have been responsible.
"We heard a loud sound and I looked at the sky to see if it was raining because I thought it was thunder but the sky was clear," said Kuwaiti tourist Farah Zamani, 24, who was shopping at one of the covered bazaars with her father and sister.
The dull thud of the blast was heard in districts of Istanbul several kilometres away, residents said. Television footage showed a police car which appeared to have been overturned by the force of the blast.
Tourist sites including the Hagia Sophia and nearby Basilica Cistern were closed on the governor's orders, officials said.
"At first we thought it was percussion bomb, it was so loud. They attacked Sultanahmet to grab attention because this is what the world thinks of when it thinks of Turkey," said Kursat Yilmaz, who has operated tours for 25 years from an office by the square.
"We're not surprised this happened here, this has always been a possible target," he said.
Ambulances ferried away the wounded as police cordoned off streets. The sound of the call to prayer rang out from the Blue Mosque as forensic police officers worked at the scene.
"It was unimaginable," the police officer who had been working on the square said, describing an amateur video he had seen of the immediate aftermath, with six or seven bodies lying on the ground and other people seriously wounded.
Just over a year ago, a female suicide bomber blew herself up at a police station for tourists off the same square, killing one officer. That attack was initially claimed by a far-left group, the DHKP-C, but officials later said it had been carried out by a woman with suspected militant links.
"Ambulances started rushing in and I knew it was a bomb right away because the same thing happened here last year," said Ali Ibrahim Peltek, 40, who operates a kiosk selling snacks and drinks on the square.
"This is not good for Turkey but everyone was expecting a terrorist attack," he said.
Turkey has become a target for IS, with two bombings last year blamed on the radical group, in the town of Suruc near the Syrian border and in the capital Ankara, the latter killing more than 100 people.
Violence has also escalated in the mainly Kurdish southeast since a two-year ceasefire collapsed in July between the state and the Kurdistan Workers Party (PKK) militant group, which has been fighting for three decades for Kurdish autonomy.
The PKK has however generally avoided attacking civilian targets in urban centres outside the southeast in recent years.
Turkey also sees a threat from the PYD and YPG, Kurdish groups in Syria which are fighting IS and with US backing, but which Ankara says have close links to the PKK.
"For us, there is no difference between the PKK, PYD, YPG, DHKP-C or whatever their abbreviation may be. One terrorist organisation is no different than the other," Erdogan said, vowing that Turkey's military campaign against Kurdish militants in the southeast would continue.
Davutoglu's office imposed a broadcasting ban on the blast, invoking a law which allows for such steps when there is the potential for serious harm to national security or public order.
The attack raised fears of further damage to Turkey's vital tourism industry, already hit by a diplomatic row with Moscow which has seen Russian tour operators cancel trips.
But Yilmaz, the tour operator, said he had sold a package to a tourist from Colombia just an hour after the blast.
"The reality is the world has grown accustomed to terrorism. It's unfortunate, and I wish it weren't true, but terrorism now happens everywhere: Paris, Germany, California, and people are used to it," he said.
"The agenda changes quickly in this age. If tourism is affected by this, it will be temporary. These things pass, but the Hagia Sophia and the Sultanahmet mosque are eternal."