A car bombing struck a busy market in the northern Syrian town of Afrin on Sunday, killing at least eight people and wounding at least a dozen more.
The UK-based Syrian Observatory for Human Rights said the explosion in the Al Hal market took place near the offices of a Turkey-backed Syrian rebel group.
The number of casualties from the attack is expected to rise as victims succumb to critical wounds, the monitor said.
The explosion is at least the third to hit Afrin in less than one week. Earlier on Friday, four members of the Turkey-backed Islamic Front rebel group were killed in a separate explosion, according to the SOHR. Another explosion on Thursday killed four people, including at least one rebel fighter.
A picture posted by the activist-run Zaman Al Wasel media outlet on Twitter showed the remains of a charred vehicle at the site of Sunday's blast.
Another video posted on social media networks showed men carrying what appeared to be a wounded man out of the market. The video also showed torched vehicles and destroyed stalls.
It was not immediately clear who was behind the attack but the area has seen a number of confrontations in recent months between Turkey-backed rebel groups vying for control over Afrin.
The explosion comes at a time of increased tension between Ankara and Syria's Kurds after President Recep Tayyip Erdogan last week threatened to launch a new offensive on Kurdish-held regions in Syria overlooking the Turkish border.
The region of Afrin was previously controlled by Kurdish groups, who liberated the area from ISIS in 2016. But, in March of this year, Turkish troops and Ankara-backed Syrian rebels pushed fighters with the Peoples Protection Units (YPG) from the area.
The Turkish defence ministry said a Turkish soldier was killed on Thursday in Afrin after being shot by members of the Kurdish People's Protection Units (YPG) militia from the nearby city of Tal Rifaat, east of Afrin.