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.

It was the deadliest attack in Turkey in over five years. Authorities stated that they were investigating whether the bomb was set off 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,” Before flying to Indonesia for the Group of 20 summit, Mr. Erdogan spoke to reporters.

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. Turkish officials had already put the number of injured at 81, with two people in critical condition.

The blast took place in front of a Istiklal Avenue is a clothing store. It is a wide pedestrian street that runs alongside historic buildings, shops, restaurants, and shops. The tram, which runs red-and-white, passes through the area. This area is bustling with tourists and Turks from all over the globe, who stroll, shop, watch street performers, and buy Turkish ice cream and roasted chestnuts.

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.

The area around Istiklal, like many other areas of Turkey that depend on tourism for their economy, has been affected by travel bans and fears about coronavirus infections in recent years. However, the area has seen a rebound this summer due to the waning of the pandemic and the strong Turkish lira making Turkey an attractive tourist destination.

According to social media videos, around 4:20 PM Sunday saw a loud boom and an orange fireball rising to the sky.

Security forces cordoned the blast site with ambulances and sirens blasting, while ambulances raced to the scene. The helicopter was circling overhead.

“I first thought it was a natural gas explosion,” Serhat Sen (30-year-old realty commissioner) was just half a block from the blast site on his motorbike.

“People were scared, crying, running away desperately,” Mr. Sen. “I started trembling. If I had been in a bit of a hurry, I would have been there.”

The bombing ended a five year stretch in which Turkey appeared more advanced than the previous deadly attacks that struck its cities.

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. The attack happened just weeks after 38 people died and over 100 were injured in explosions that occurred outside a soccer arena.

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. The Islamic State, which was the ruler of a so-called caliphate, in Syria and Iraq, until early 2019, inspired jihadists to attack 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 is a doctoral student. wrote on TwitterAccording to him, the explosion had brought back memories of an attack wave many years ago.

Condolences came in from Europe and the Middle East. Jens Stoltenberg was the secretary general for NATO. He said the alliance had been affected by the tragedy. “stands in solidarity” Turkey. The soccer match that was scheduled for nearby was also cancelled by the Turkish Football Federation.

Carlotta Gall Contributed reporting