The Syrian Observatory for Human Rights, updating an earlier toll, said 20 people were wounded as one car detonated at a checkpoint just outside the crossing and another inside the post.
The border crossing in Idlib province of northwest Syria is held by Islamist and moderate rebels who have been locked in fierce fighting with jihadists from the Islamic State of Iraq and the Levant in recent weeks.
ISIL fighters today took control of the Jarrah military airport in the northern province of Aleppo that had been in rebel hands since February 2013.
ISIL, today, imposed a Taliban-style ban on music and smoking in Raqa, declaring them un-Islamic.
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The group added it had taken the step because musical instruments and singing are "proscribed in Islam because they distract from remembering God and the Koran".
Such bans are reminiscent of those the Taliban imposed on television, cinema and music in Afghanistan when in power up until 2001.
ISIL has alienated activists and other opposition fighters in Syria, who accuse it of imposing a reign of terror on areas where it operates.
Its actions provoked a backlash from powerful rebel groups in early January, and the group is now fighting opposition forces in several parts of northern Syria.
The Britain-based Observatory also reported heavy clashes between jihadists and rebels on the outskirts of the town of Azaz in Aleppo province, near the border with Turkey.
Rebel groups in the town shelled areas where ISIL fighters were with mortar rounds, the Observatory said.