Twenty-nine victims were under the age of 18, reports said, with one official saying 22 were under the age of 14. The death toll rose to 54 on Monday.
The suicide bomber himself was a child aged 12-14, President Recep Tayyip Erdogan has said.
Mr. Erdogan has blamed so-called Islamic State (IS) for the attack.
Gaziantep, near the Syrian border, is known to contain several IS cells.
On Monday, Turkish officials were awaiting the results of DNA tests as they tried to identify the suicide attacker, the Hurriyet newspaper said.
It added that the type of bomb, which contained scraps of metal, was similar to those used in previous attacks on pro-Kurdish gatherings.
Kurdish fighters, backed by the US-led coalition, have been at the forefront of the fight against IS in Syria.
“We don’t yet know the nationality of the attacker – Syrian, Turkish or other – but his generation has grown up formed by the Syrian conflict which tore away his childhood innocence and instilled in him the desire to kill.
There is still no official claim of responsibility for the attack but the group calling itself Islamic State remains the prime suspect.
The group is facing the loss of territory close to the Turkish border at the hands of Kurdish forces in Manbij and also a potential operation in Jarablus by the Free Syria Army – this could be an attempt to hit back.
It’s also a reminder that their cells are still active in Turkey and they can strike with devastating impact.
Prosecutors said a search was also under way for two people believed to have accompanied the suspected attacker to the wedding party but who left before the blast.
In a defiant speech on Monday, Turkish Foreign Minister Mevlut Cavusoglu said IS should be “completely cleansed” from the border area with Turkey.