At least eight people were killed on Thursday when a car bomb exploded in a busy market in the northwest Syrian city of Afrin, under control of Turkey-backed rebel groups, witnesses and a rescuer said.
They said the blast also wounded at least 30.
The Turkish military helped by its Syrian rebel allies seized Afrin, a mainly Kurdish city, from the Kurdish YPG militia in March 2018 in a major offensive.
Turkish forces have since carved out a buffer zone inside northern Syria that extends along most of the countries' border.
Videos posted on social media showed extensive damage to the market area with fires burning. Reuters could not immediately vouch for their authenticity.
Similar car blasts frequently hit crowded civilian areas in the mainly Arab populated towns near the border with Turkey under the control of Turkish-backed forces.
Residents and rebels in the rebel-held northwest blame the YPG for the attacks.
The Kurdish-led forces say they are engaged in a guerrilla campaign against Turkish forces but deny they target civilians.
Turkish forces launched their offensive inside Syria this month with a view to setting up a safe zone in mainly Arab populated border areas east of the Euphrates that the Kurdish-led forces control. It has pushed Kurdish fighters out of parts of the strip.