At least three civilians, including a child, were killed in artillery strikes by the Assad regime forces in Syria's opposition-held northwest, a war monitor said Wednesday.

The shelling lasted all day at several locations in the region, an AFP correspondent there said, adding that the Hayat Tahrir al-Sham (HTS) militant group targeted government positions in retaliation.

"Three civilians including a child were killed in heavy artillery fire in the town of Kafr Nuran in Aleppo's western countryside," the Britain-based Syrian Observatory for Human Rights said.

Two others were injured, added the Observatory, which relies on a wide network of sources on the ground in Syria.

The shelling damaged a house in the town of Kafr Nuran, an AFP correspondent said.

Residents in the town told AFP that the artillery fire hit a neighborhood where some people had gathered to buy watermelons.

Earlier Wednesday, HTS rocket fire had killed a Syrian soldier in regime-held areas of Idlib province, the Observatory said.

Nearly half of Idlib province, including the provincial capital of the same name, as well as parts of the adjacent provinces of Aleppo, Hama and Latakia, make up the last of Syria's opposition-held areas.

Despite periodic clashes, a cease-fire deal brokered by regime ally Moscow, as well as Türkiye – which supports rebel groups in Syria – has largely held in the northwest since March 2020.

The Idlib region is home to about three million people, around half of them displaced.

Syria's war has killed more than half a million people and displaced millions since erupting in 2011 with a brutal crackdown on anti-government protests.