The students from the Federation of Socialist Youth Associations had been planning to build a library, plant a forest and build a playground, a member of the group wounded in the blast told Reuters.
“We defended it together and we will rebuild it together”, read one of the group’s banners at the scene.
The explosion comes weeks after the Turkish government deployed additional troops and equipment along parts of its border with Syria – amid concerns fighting there could spill over into Turkey.
Turkish President Tayyip Erdogan said 28 people were killed and around 100 wounded, though it is thought that the death toll could rise.
Turkish newspaper The Hurriyet Daily said the attacker was a young woman, though this has not been confirmed.