MEHR: Turkey's Interior Minister Suleyman Soylu said police had detained 22 suspects, including the person who had planted the bomb.
"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 the historic Istiklal Avenue, a popular spot for shoppers and tourists with a tramline running its length.
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, Reuters reported.
Soylu added that the bomber had passed through Afrin, another region in northern Syria.
Six people died and 81 were injured when Istanbul’s popular pedestrian thoroughfare İstiklal Avenue was hit by a bomb attack that Turkey’s president described as an act of terrorism.