At least six people have been killed and 81 injured in an explosion in a busy area of central Istanbul, Turkish officials said.
The explosion occurred on Sunday at around 16:20 local time (13:20 GMT) on a shopping street in the Taksim Square area.
The interior minister said that now a suspect has been arrested.
Vice President Fuat Oktay had earlier said that the blast was believed to be a terrorist attack carried out by a woman.
President Recep Tayyip Erdogan said that the criminals will be punished.
Speaking at a news conference in Istanbul, he condemned what he called a “disgusting attack” and said the “smell of terror” was in the air.
Justice Minister Beker Bozdag told Turkish media that a woman sat on a bench in the area for more than 40 minutes and left minutes before the explosion.
On Monday morning, Interior Minister Suleyman Soylu said police had arrested a person who set off the bomb, and blamed the Kurdistan Workers’ Party (PKK).
The PKK is a militant group that calls for an independent Kurdish state within Turkey. The European Union and the United States consider it a terrorist organization.
No one has yet claimed responsibility for the blast.
Government Minister Daria Yanak wrote in a tweet that an employee of the government ministry and his young daughter are among the victims.
JEE News Reporter said there was a heavy police presence around Istiqlal Street, which had been cordoned off. Helicopters circled overhead as ambulances rushed back and forth.
Many shopkeepers standing at their doors on the normally bustling street were stunned, he said, adding that the incident would come as a shock to many in the city.
Hayat, who was at an Internet cafe on Istiqlal Street when the explosion occurred, said that a commotion broke out after the explosion.
“I saw people running around and injured people passing from the internet cafe to the hospital,” he said. “It was an obsession.”
Another witness, Cemal Denizci, was about 50m (54 yards) away when the explosion occurred. “There was black smoke,” he told AFP.
Ayup, 20, told JEE News there was “fear” among Istanbul residents after the attack, adding that more people may choose to stay away from crowded areas such as Taksim.
After this attack, condolences are being expressed for Turkey from all over the world.
The United States said it stood “shoulder-to-shoulder” with its NATO ally in the “war on terror,” according to a statement from White House press secretary Karen Jean-Pierre.
French President Emmanuel Macron tweeted in Turkey: “We share your pain, we are with you in the fight against terrorism.”
Ukrainian President Volodymyr Zelensky also tweeted in Turkey: “The pain of the friendly Turkish people is our pain.”
Countries including Pakistan, Italy and Greece also expressed solidarity.
Istiqlal Street – one of the city’s main arteries that is usually packed with shoppers – was previously hit by a suicide bomber in 2016.
