At least 15 people were killed and 51 wounded on Friday night in Lashkargah City in Helmand after a suicide bomber detonated a car laden with explosives.
Officials confirmed that children were among those killed and wounded.
Helmand governor's spokesman Omar Zwak said the explosion occurred outside a stadium in Lashkargah City as people were leaving a wrestling match.
President Ashraf Ghani in a statement condemned the attack and said "the enemies of Afghanistan cannot prevent the celebration of traditional, religious and cultural events in the country".
UNAMA also confirmed the incident and said on twitter “verifying disturbing reports of attack outside sports stadium in Helmand.
“Attacks directed at civilians are clear violations of international humanitarian law and may amount to war crimes.”
No group has claimed responsibility for the explosion.