ISTANBUL — A bomb attack struck a bustling pedestrian thoroughfare in central Istanbul on Sunday, killing at least six people, in what officials said could be a terrorist attack, and shattering a sense of calm as Turkey’s tourist industry works to recover from the pandemic.
The attack was the deadliest in Turkey in more than five years, and the authorities said they were looking into the possibility that the bomb had been detonated by a woman. Turkey’s president, Recep Tayyip Erdogan, vowed to punish those behind the blast, without accusing any specific group.
“Efforts to make Turkey and the Turkish nation surrender by terror will not reach their aim today, as they did not in the past,” Mr. Erdogan told reporters before flying to Indonesia for the Group of 20 summit.
The explosion shook the heart of one of Istanbul’s most popular districts, a short walk from Taksim Square, leaving bloodied passers-by strewn about the pavement and sending waves of visitors rushing from the area. By Sunday evening, Turkish officials had put the number of people wounded at 81, with two in critical condition.
The blast occurred in front of a clothing store on Istiklal Avenue, a broad pedestrian street lined with historic buildings, shops and restaurants and traversed by a red-and-white tram. The area is crowded day and night with Turks and tourists from around the world strolling, shopping, watching street musicians and buying roasted chestnuts and Turkish ice cream.
The avenue was even more crowded than usual on Sunday because one of Turkey’s premier soccer teams was scheduled to play nearby in the evening, drawing fans to the neighborhood.
Like many parts of Turkey where the economy relies on tourism, the area around Istiklal had suffered in recent years as travel bans and fears of coronavirus infection kept many tourists away. But the area rebounded this summer as the pandemic waned and the weak Turkish lira made Turkey an attractive tourist destination.
About 4:20 p.m. Sunday, a large boom shook the street and an orange fireball rose to the sky, according to videos shared on social media.
Ambulances with sirens blaring rushed to the area as security forces cordoned off the blast site. A police helicopter circled overhead.
“I first thought it was a natural gas explosion,” said Serhat Sen, a 30-year-old real estate commissioner, who was on his motorbike a little more than half a mile from the blast site.
“People were scared, crying, running away desperately,” Mr. Sen added. “I started trembling. If I had been in a bit of a hurry, I would have been there.”
The bombing broke a five-year stretch in which Turkey appeared to be moving past the deadly attacks that had struck its cities in previous years.
Early on New Year’s Day 2017, at least 39 people were killed and dozens of others wounded when a gunman attacked a crowded Istanbul nightclub. That attack came a few weeks after at least 38 people were killed and more than 100 wounded in two explosions, including one outside of a soccer stadium.
The Turkish state has also been at war for decades with Kurdish militants based in the country’s southeast; they have launched deadly attacks on civilians and security forces. And jihadists who belonged to or were inspired by the Islamic State, which ruled a so-called caliphate in Syria and Iraq until early 2019, often attacked public places in Turkey, killing civilians.
In October 2015, two explosions rocked the heart of Ankara, the Turkish capital, killing more than 100 people who had gathered for a peace rally, in what officials called the deadliest terrorist attack in modern Turkey’s history. The blasts occurred near Ankara’s main train station just as Kurds and leftists were preparing to march to protest the resumption of armed conflict between the Turkish state and Kurdish militants.
But such attacks had grown rare in the last few years, which is why people near the site Sunday’s bombing felt such shock.
“I feel paralyzed by the fear of how I am going to go out,” Ziya Aydi, a doctoral student, wrote on Twitter, saying the explosion had revived memories of a wave of attacks years ago.
Condolence messages poured in from Europe, the Middle East and beyond, with Jens Stoltenberg, the secretary general of NATO, saying the alliance “stands in solidarity” with Turkey. The Turkish Football Federation also postponed the soccer game that had been scheduled to take place nearby.
Carlotta Gall contributed reporting.