Turkey sent tanks across the border to help Syrian rebels drive the Islamic State (IS) group out of the frontier town of Jarablus last week in an escalation of its involvement in the Syrian civil war.
The operation - labelled Euphrates Shield - is also aimed at pushing back US-allied Kurdish forces.
The fighting pits a Nato ally against a US-backed proxy that is the most effective ground force battling IS in Syria.
A Turkish soldier was killed by a Kurdish rocket attack late on Saturday, the first such fatality in the offensive.
Various factions of the Turkey-backed Syrian rebels said yesterday they have seized at least four villages and one town from Kurdish-led forces south of Jarablus.
One of the villages to change hands was Amarneh, where clashes had been fiercest. Rebels posted pictures from inside the village.
Ankara is deeply suspicious of the Syrian Kurdish militia that dominates the US-backed Syria Democratic Forces (SDF). Turkish leaders have vowed to drive IS and the Kurdish People’s Protection Units, or YPG, away from the border.
Turkey is part of the US-led coalition fighting IS but the airstrikes that began on Saturday marked the first time it has targeted Kurdish-led forces in Syria.
The Britain-based Syrian Observatory for Human Rights said the bombing killed at least 20 civilians and four Kurdish-led fighters in Beir Khoussa, a village about nine miles south of Jarablus, and another 15 in a village to the west.
ANHA, the news agency of the Kurdish semi-autonomous areas, said Beir Khoussa has “reportedly lost all its residents.”
SDF spokesman Shervan Darwish said the airstrikes and shelling started overnight and continued yesterday along the front line, killing many civilians in Beir Khoussa and nearby areas. He said the bombing also targeted Amarneh village. He said 50 Turkish tanks were taking part in the offensive.
Syrian state news agency SANA reported that 20 civilians were killed and 50 wounded in Turkish artillery shelling and airstrikes, calling it Turkish “encroachment”.