State news agency SANA said the blast occurred in the village of Suluk near the Turkish border, putting the death toll at five people and reporting several more were injured.
A similar death toll was also given by the Turkey-based Syrian National Coalition and the Britain-based Syrian Observatory for Human Rights, an opposition war monitor. The observatory, which has a network of activists in Syria, said 20 others were also wounded.
Suluk is controlled by Turkey-backed opposition fighters, and is near the Syrian border town of Tal Abyad in Raqqa province.
Turkish troops and Turkey-backed fighters captured Tal Abyad and Suluk from Kurdish-led fighters in October. That was during Turkey's invasion of northeastern Syria, in which it pushed back Syrian Kurdish fighters from some border areas.
Explosions in north Syria areas controlled by Turkey-backed opposition fighters killed scores of people in recent weeks.
Turkey blames Syrian Kurdish fighters for these attacks, a claim that the Kurds deny.