Syrian Kurdish fighters carried out an attack early Monday in northern Syria, killing at least five members of Türkiye-backed Syrian opposition forces, activists said.

The attack south of the northern town of Afrin, which is held by the Türkiye-backed forces, took place shortly after midnight on Sunday, according to the Britain-based Syrian Observatory for Human Rights.

The Observatory, an opposition war monitor, said the attack was carried out by the Afrin Liberation Forces, a Kurdish faction allied with the main Kurdish group in Syria known as the People’s Protection Units (YPG). The group has claimed scores of attacks against Türkiye-backed Syrian fighters.

Syria-based opposition activist Taher al-Omar said the attack took place about 20 kilometers (12 miles) south of Afrin. According to al-Omar, five members of the Türkiye-backed faction Failaq al-Sham were killed. The Observatory said six died, but different tolls are not uncommon in the immediate aftermath of such attacks.

Afrin has been under the control of Türkiye and its allied Syrian opposition fighters since 2018, following a Türkiye-backed military operation that pushed Syrian Kurdish fighters and thousands of Kurdish residents from the area.

Since then, the town and surrounding villages have been the site of attacks on Turkish and Türkiye-backed targets. Ankara considers Syrian Kurdish fighters who control a swath of Syrian territory along Türkiye’s border to be terrorists, allied with Kurdish insurgents within Türkiye.

Also Monday in northern Syria, Kurdish fighters fired several rockets at a Turkish army base near the town of Azaz, the Observatory and al-Omar said. There was no immediate word on casualties.

The violence comes a day after two explosions in northern Syria killed eight people, including three members of a Syrian Kurdish-led group in the town of Manbij.