The youth activists, most of them were university students, were holding a news conference when the bomb ripped through the cultural centre. They had been planning to travel to Syria to help rebuild the town of Kobane.
Kobane has been a battleground between militants from the Islamic State (ISIS) group and Kurdish fighters since September last year, when the militant group overran the town, forcing most of its residents to flee into Turkey.
"The suspect's international and domestic links is being investigated," said Prime Minister Ahmet Davutoglu,who is set to visit the blast site.
According to him, Islamic State is suspected to be behind the blast.
A cabinet meeting on Wednesday will examine additional security measures along the border with Syria.