The Britain-based Syrian Observatory for Human Rights reported that 14 people, including nine civilians, were killed Saturday in the town of al-Bab.
The Aleppo Media Center, an activist collective, said 12 people were killed in the blast near a bus station in the town.
Different casualty figures are common in the immediate aftermath of explosions.
No one claimed responsibility for the attack.
Explosions have killed and wounded scores of people in Turkish-held areas of northeastern Syria in recent months.
Those attacks have come amid an expanding Turkish invasion of Syrian Kurdish-held towns and villages along a stretch of the border.