A bomb exploded in a shopping area in a northern Syrian city held by pro-Turkish forces early Sunday, killing eight people and wounding more than 20 others, a war monitor said.

At least "eight people were killed and 23 others wounded" when "a car bomb exploded in the middle of a popular market" in Aleppo province's Azaz said the Syrian Observatory for Human Rights.

The Britain-based Observatory, which has a network of sources inside Syria, said the blast caused "significant damage" and sparked a fire.

An AFP correspondent saw emergency responders working at the scene and the remains of a mangled vehicle.

Syria's war began after the government repressed peaceful protests in 2011 and escalated into a deadly conflict that pulled in jihadists and foreign armies.

The war has killed more than 507,000 people, displaced millions and battered the country's infrastructure and industry.

Turkey has launched successive military offensives in Syria, most of them targeting Kurdish militants that Ankara links to the Kurdistan Workers' Party (PKK), which has waged a decades-long insurgency against the Turkish state.

Turkish troops and their Syrian proxies hold swathes of the border, including several major cities and towns such as Azaz.