Four Kurdish fighters at the checkpoint were killed, as were two children, it said. More children were among 10 people wounded.
Kurdish fighters in the area are battling jihadist fighters from the Islamic State group.
The war in Syria began in March 2011 with peaceful protests against President Bashar al-Assad's government, but quickly escalated into an armed rebellion after a brutal regime crackdown.
According to the Britain-based Observatory, which relies on a broad network of activists and medics for its information, more than 200,000 people have been killed in the conflict.
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Kurdish fighters in the area are battling jihadist fighters from the Islamic State group.
The war in Syria began in March 2011 with peaceful protests against President Bashar al-Assad's government, but quickly escalated into an armed rebellion after a brutal regime crackdown.
According to the Britain-based Observatory, which relies on a broad network of activists and medics for its information, more than 200,000 people have been killed in the conflict.
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