Turkey's Interior Minister Suleyman Soylu blamed Kurdish militants on Monday for a blast that killed six people in Istanbul's main shopping street, and said police had detained 22 suspects, including the person who had planted the bomb.
Soylu said the order for the attack on Istanbul's Istiklal Avenue was given in Kobani, a city in northern Syria, where Turkish forces have carried out operations against the Syrian Kurdish YPG militia in recent years.
"We have evaluated that the instruction for the attack came from Kobani," Soylu said, adding that bomber had passed through Afrin, another region in northern Syria.
"The person who carried out the incident, left the bomb, was detained. Previously, around 21 other people had been detained," Soylu said.
Television news reports showed images of a person, who appeared to be a woman, leaving a package below a raised flower bed on Istiklal Avenue, a popular spot for shoppers and tourists, with a tramline running the length of the street.
Fifty people were discharged from the hospital after Sunday's attack, which sparked concerns that Turkey could be targeted with more bombings and attacks, like the series of attacks that it suffered between mid-2015 and 2017.
Istanbul has been targeted in the past by Kurdish, Islamist and leftist militants. An offshoot of the Kurdistan Workers Party (PKK) claimed twin bombings outside an Istanbul soccer stadium in December 2016 that killed 38 people and wounded 155.
Of those wounded on Sunday, two of the five people being treated in intensive care were in critical condition, the Istanbul Governor's Office said. They were among the 31 wounded still in the hospital.
Hundreds of people fled the historic Istiklal Avenue after the blast on Sunday, as ambulances and police raced in. The area, in the Beyoglu district of Turkey's largest city, had been crowded as usual at the weekend with shoppers, tourists and families.
Video footage obtained by Reuters showed the moment the explosion occurred at 4.13 pm (1313 GMT), sending debris into the air and leaving several people lying on the ground, while others stumbled away.
All six killed in the attack were Turkish citizens.
Ankara says the YPG, which Washington has supported in Syria, is a wing of the PKK.
Turkey has carried out three incursions in northern Syria against the YPG, with the latest in 2019, seizing hundreds of kilometres of land. President Tayyip Erdogan has said this year that Turkey will again target the YPG.
The PKK has led an insurgency against the Turkish state since 1984 and more than 40,000 people have been killed in clashes. The PKK is considered a terrorist organisation by Turkey, the European Union and the United States.
Condemnations of the attack and condolences for the victims poured in from several countries including Azerbaijan, Britain, Egypt, Greece, Italy, Pakistan and Ukraine.