Footage posted online showed ambulances, fire engines and police at the scene on Istiklal Avenue, a typically busy thoroughfare popular with tourists and locals and lined with shops and restaurants. In one video, a loud bang and flames were heard as the pedestrians turned and fled. President Recep Tayyip Erdogan called the explosion a “treacherous attack” and said the perpetrators would be punished. “It would be wrong to say that this is undoubtedly a terrorist attack, but the initial developments and the initial information from my governor is that it smacks of terrorism,” Erdogan told a news conference. A forensic pathologist works after the explosion on the busy Istiklal pedestrian street on Sunday. (Kemal Aslan/Reuters) Erdogan said six people were killed. Vice President Fuat Oktai later updated the number of injured to 81, with two in serious condition, and also said it appeared to be a terrorist attack. Erdogan did not say who was behind the attack, but said “attempts to defeat Turkey and the Turkish people through terrorism will fail today as they did yesterday and as they will fail again tomorrow.” No one has claimed responsibility for the blast, but Istanbul and other Turkish cities have been targeted in the past by Kurdish separatists, Islamist militants and other groups.

‘People froze’: witness

The president said investigations are continuing by police and the governor’s office, including reviewing video from the area. “When I heard the explosion, I was petrified, people froze, looking at each other. Then people started running away. What else can you do,” said Mehmet Akous, 45, a restaurant worker in Istiklal. “My relatives called me, they know I work in Istiklal. I reassured them,” he told Reuters. People react after the explosion on Istiklal Street. The area was packed as usual on the weekend with shoppers, tourists and families. (Kemal Aslan/Reuters) A helicopter flew over the blast site and several ambulances were stationed in nearby Taksim Square. Kasimpasa Police Station said all crews were at the scene, but did not provide further details. The Turkish Red Crescent said the blood was being transported to nearby hospitals.

Past Deadly Bombings

Many foreign governments expressed their condolences, including neighboring Greece with which relations are strained. Prime Minister Kyriakos Mitsotakis said he was “shocked and saddened by the news of the heinous attack”. If confirmed, it would be the first major bomb blast in Istanbul in several years. Turkey was hit by a series of bombings between 2015 and 2017 that left more than 500 civilians and security personnel dead. Some of the attacks were carried out by Islamic State, while others were carried out by Kurdish fighters who have led a decade-long insurgency against the Turkish state for increased autonomy or independence. Security and ambulances are at the scene after Sunday’s explosion. (Francisco Seco/The Associated Press) Turkey has been fighting the militants — known as the PKK and considered a terrorist organization by Turkey, the United States and the European Union — in the country’s southeast for years. In one attack, twin bombings outside an Istanbul football stadium in December 2016 killed 38 people and injured 155 in an attack claimed by an offshoot of the PKK. After the series of attacks, Turkey launched cross-border military operations in Syria and northern Iraq against Kurdish fighters, while also cracking down on Kurdish politicians, journalists and activists at home through blanket terrorism laws that critics say are a way to silence the disputants. Turkey’s media watchdog imposed temporary restrictions on reporting on the blast — a move that bans the use of close-up videos and photos of the blast and its aftermath. The Supreme Broadcasting Council has imposed similar bans in the past, following attacks and accidents. Access to some content on Twitter and other social networking sites, such as videos, was restricted.