A suicide car bomb in a northwestern Syrian city held by Turkey-backed rebels killed at least 14 people on Sunday, according to a UK-based war monitor.

Four children were among those killed in the explosion in Azaz, a city at the heart of a Turkish zone of influence in northern Aleppo province, said the Syrian Observatory for Human Rights.

The attack also wounded more than 20 people, according to the Observatory.

“Many people were leaving evening prayers when the explosion happened,” Observatory head Rami Abdul Rahman told AFP.

It was not clear who was behind the attack.

The bombing comes one day after a similar blast killed 10 people and wounded 20 in the northeastern city of Raqa.

Turkey launched Operation Euphrates Shield in 2016, seizing more than 2,000 square kilometers of territory in northern Syria, including Azaz, clearing the area of the ISIS militants, while preventing any Kurdish advance in the region.

Ankara keeps Turkish troops and intelligence forces in the area and still backs the local police forces.

– with reporting by AFP