Sunday’s blast is the first such incident in Istanbul, Turkey’s largest city, in several years.

Turkey was hit by a string of deadly bombings between 2015 and 2017 by ISIL (ISIS) and outlawed Kurdish groups.

According to official figures at the time of publishing at least six dead, 53 injured in Istiklal blast 

Turkish President Recep Tayyip Erdogan has said that the explosion in Istanbul’s Istiklal Street was caused by a “bomb attack,” adding that six people died in the incident.

Speaking before his departure to the G-20 summit in Indonesia on Sunday, Erdogan said the explosion was a “treacherous attack” and its perpetrators would be punished.

Another 53 were wounded, according to information he received from the Istanbul governor.

A witness of the explosion in Istanbul’s Istiklal Street talks about the moments of panic during the incident.

“I was 50-55 metres (yards) away, suddenly there was the noise of an explosion. I saw three or four people on the ground,” witness Cemal Denizci, 57, told the AFP news agency.

“People were running in panic. The noise was huge. There was black smoke,” he said.

Istiklal avenue is a crowded thoroughfare popular with tourists and locals and lined by shops and restaurants.

A video posted online shows flames erupting and a loud bang, as pedestrians turn and run away.

Other footage shows ambulances, fire trucks and police at the scene. Social media users said shops were shuttered and the avenue closed down.