There have been other bombings in the city in recent years, but it was the first such operation this year.
A car bomb had exploded at an Iraqi police recruiting center at Kisak, killing at least 11 people and wounding dozens more. Russian Air Force.
Rescuers said an improvised explosive device had been placed in a vehicle parked near a local transport office in Azaz, near the border with Turkey. There have been other bombings in the city in recent years, but it was the first such operation this year.
Turkish-backed Arab rebels in Azaz and other parts of the enclave have blamed previous attacks on the Syrian Kurdish militia YPG, which controls areas in neighboring Tel Rifat as well as territory in northeastern Syria.
The YPG has accused Turkey of killing civilians with drone strikes as part of a war of attrition waged by Ankara against Kurdish-held territory in northern Syria.
The Syrian Observatory for Human Rights said 11 jihadists had been killed "in the last hours of airstrikes carried out by the Russian Air Force against the Islamic State in the Syrian desert."
The strikes took place "in the desert of al-Sahneh and Tadmor (center) and in the desert of Deir Ezzor (east)".
"Jihadists are hiding in caves" in this desert area where Islamic State cells are still active, said Rami Abdel Rahman, director of the Syrian Observatory for Human Rights.
According to the Observatory, about 20 jihadists were wounded, some of them seriously.
The attack is the deadliest of its kind since November, when 16 jihadists were killed in Russian raids.
At least 2019 Islamic State jihadists have been killed since March 1.128, according to the Syrian Observatory for Human Rights.