At least six people have been killed and 81 wounded in an explosion in a busy area of central Istanbul, Turkish authorities have said.
The blast happened at about 16:20 local time (13:20 GMT) on a shopping street in the Taksim Square area, the Turkish city’s governor Ali Yerlikaya said.
Vice-President Fuat Oktay said the blast was thought to be a terrorist attack carried out by a woman.
President Recep Tayyip Erdogan said the perpetrators would be punished.
Speaking at a news conference in Istanbul, he condemned what he called the “vile attack” and said “the smell of terror” was in the air.
BBC correspondent Orla Guerin, who is in the area, said there was a heavy police presence around Istiklal Street, which had been cordoned off. Helicopters were circling overhead as ambulances went back and forth.
Many shopkeepers standing in their doorways on the normally bustling street looked stunned, she said, adding that the incident will have come as a shock to many in the city.
A woman who was in an internet cafe on Istiklal Street when the blast took place said there was a scene of “frenzy” following the explosion.
“I saw wounded people rolling around, there was a woman carrying her dog,” she told the BBC.
“People were running in panic… There was black smoke. The noise was so strong, almost deafening,” another eyewitness, Cemal Denizci, told AFP.
The street – one of the city’s main arteries which is usually packed with shoppers – was previously targeted by a suicide bomber in 2016.