At least four people have been killed and 38 injured after an explosion on a busy pedestrian street in central Istanbul, the city’s governor has said.

People ran away following the blast on Istiklal Avenue in the Taksim area.

A video posted online showed flames erupting and a loud bang.

Istanbul’s governor Ali Yerlikaya tweeted the death toll and said the injured were being treated.

He said: “According to initial reports, four people lost their lives and 38 were injured in the explosion that took place on Istiklal Street.

“Our wounded are being treated.

“We wish God’s mercy on those who lost their lives and a speedy recovery to the injured.”

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He said the explosion occurred around 4.20pm local time (1.20pm GMT).

State broadcaster TRT showed videos of ambulances and police headed to the scene.

Social media users said shops were shuttered and the avenue closed down.

“When I heard the explosion, I was petrified, people froze, looking at each other. Then people started running away. What else can you do,” Mehmet Akus, 45, a worker in a restaurant on Istiklal, told Reuters.

“My relatives called me, they know I work on Istiklal. I reassured them,” he added.

The cause of the blast was not immediately known.

Five prosecutors have been assigned to investigate the explosion, state-run Anadolu news agency said.

“My condolences to those who lost their lives in the explosion on Istiklal Avenue,” mayor Ekrem Imamoglu tweeted.

Turkey’s RTUK regulator imposed a broadcast ban on coverage of the blast around an hour after it occurred. It prevents broadcasters from showing videos of the moment of the blast or its aftermath.

Istiklal Avenue is a pedestrian thoroughfare popular with tourists and locals and is lined with shops and restaurants.

Turkey suffered several deadly bombings between 2015 and 2017 by Islamic State and outlawed Kurdish groups.