Turkish authorities have arrested a suspect who allegedly planted a bomb on a busy pedestrian street in Istanbul that killed at least six people and wounded 81 others, Interior Minister Suleyman Soylu said early Monday. 

The blast, which Turkish President Recep Tayyip Erdogan said "smells like terrorism," took place at 4:20 p.m. on Sunday.

Initial findings suggest the PKK/YPG terror group was behind the bomb attack, Soylu was quoted by Turkish media.

Meanwhile, condemnations of the attack and condolences for the victims have rolled in from several countries including Lebanon, Algeria and Greece.

In a statement, Lebanon's Ministry of Foreign Affairs expressed its condolences to the Turkish government and families of the victims, wishing "a speedy recovery for the injured." 

In a phone call with Erdogan, Lebanese Prime Minister Najib Mikati said his country is "confident that Türkiye will remain stronger than adversity, with the determination of its leadership and the solidarity of its people."

Istanbul and other Turkish cities have been targeted in the past by Kurdish separatists, Islamist militants and other groups, including in a series of attacks in 2015 and 2016.

"Efforts to defeat Türkiye and the Turkish people through terrorism will fail today just as they did yesterday and as they will tomorrow," Erdogan told a news conference before flying to Indonesia for a summit of the Group of 20 leading economies.

Twin bombings outside an Istanbul soccer stadium in December 2016 killed 38 people and wounded 155 in an attack claimed by an offshoot of the militant Kurdistan Workers Party, which is designated a terrorist group by Türkiye, the European Union and the United States.

(With input from agencies)