A bomb went out on a busy pedestrian street in the centre of Istanbul on Sunday, killing six people, injuring many more, and forcing many more to run as the flames rose.

Also read: Istanbul blast smells like terrorism: Turkey president Recep Tayyip Erdogan

Ambulances, fire engines, and police were seen at the site on Istiklal Avenue, a busy street lined with stores and eateries that leads to Taksim Square, in footage that was shared online. In one video, a huge blast could be heard and people could see flames as they turned and fled.

The explosion was referred to as a “treacherous attack” by Turkish President Recep Tayyip Erdogan, who also promised to punish those responsible.

Istanbul Governor Ali Yerlikaya tweeted that 53 other people had been injured in addition to the six fatalities—victim statistics that Erdogan also provided.

Erdogan did not identify the perpetrators of the incident, but he did claim that there was a “smell of terror” about it. He added that this was not yet confirmed. He claimed that the governor’s office and the police were still looking into the incident and studying video from the scene.

Also read: Where is Istiklal Avenue in Istanbul?

Between 2015 and 2017, both the outlawed Kurdish factions and the Islamic State group attacked Turkey with a series of deadly attacks. In the attacks, more than 500 civilians and security personnel died.

Also read: Explosion in Istanbul’s Istikal Avenue, 6 dead, 53 hurt

The use of up-close recordings and pictures of the explosion and its aftermath has been prohibited for the time being by Turkey’s media authority. Similar prohibitions have previously been issued by the Supreme Council of Radio and Television in the wake of attacks and accidents.

Videos on Twitter and other social media platforms were only partially accessible.