At least seven people were killed and thirty injured on Saturday in a car blast in a busy marketplace in the rebel-held Syrian town of Azaz near the Turkish border.
There was no immediate claim of responsibility.
The Arab-populated town run by Syrian rebel groups backed by Turkey opposed to Syrian President Bashar al Assad has been relatively quiet since it was hit by a car blast over two years ago.
Main towns in the northwestern border area have in recent years been frequently hit by bombings detonated in crowded civilian areas.
The civil defence forces said that at least thirty were wounded with some seriously injured transferred to local hospitals.
Residents and rebels in the mainly Arab-populated rebel-held northwest have long suspected the Kurdish led YPG who control large swathes of areas in northeast Syria and east of the Euphrates in northern Syria. Others blame groups loyal to Assad.
The YPG have long denied such claims.
