At least 21 civilians including children were killed Friday in separate bombardments in the latest flare-up of violence along Syria's northern border with Turkey, Kurdish authorities and a war monitor said.
The bloodshed comes against a backdrop of increased tensions pitting the Kurdish-led Syrian Democratic Forces (SDF) against Turkish troops and their Syrian proxies.
A pre-dawn strike by a Turkish drone that hit "a training centre for young girls" in the Shmouka area near Hasakeh in the northeast killed "four children and wounded 11", a statement from the semi-autonomous Kurdish authorities said.
The Britain-based Syrian Observatory for Human Rights, a war monitor with a broad network of sources on the ground, confirmed the toll.
In Al-Bab, a town under the control of Syrian factions loyal to Ankara, "artillery fire on a market by pro-regime forces killed 17 civilians -- including six children -- and wounded another 35," the Observatory said.
An AFP correspondent said the strike on the town near the Syria-Turkey border had ripped through the market, and described a jumble of body parts, strewn vegetables and mangled handcarts.
Residents and first responders rushed to assist and evacuate the wounded, the correspondent said.
A spokesman for the SDF, the Syrian Kurds' de facto army, denied any involvement.
Ankara considers the main Kurdish component of the SDF -- allied with the United States in the fight against Islamic State group jihadists -- to be a terrorist organisation with links to the Kurdish insurgency inside its own territory.
Turkey has been threatening since May to begin a new offensive in northern Syria, and Kurdish officials and the Observatory say Turkish drones have been launching more and more strikes on SDF-controlled areas.
Regime forces have deployed in areas controlled by Kurdish fighters near the border with Turkey as part of agreements intended to stem a fresh Turkish operation.
On Friday, President Recep Tayyip Erdogan said Turkey was not looking to seize any Syrian territory, despite stepping up its attacks in the country's north.
"We do not have eyes on the territory of Syria because the people of Syria are our brothers," Turkish media quoted Erdogan as saying.
"The regime must be aware of this."
Since the beginning of the war in Syria, Turkey has strongly opposed President Bashar al-Assad and has backed some rebel groups battling his regime.