BEIRUT (AP) — A suspected Syrian government airstrike on a market in a northwestern rebel-held town killed 13 civilians on Monday while Turkish artillery shells landed near a school in a Kurdish-held town, killing at least nine, including eight children, activists said.

The violence is part of rising tension in Syria’s north, along the border with Turkey. Syrian government troops have renewed their push to reclaim the last opposition stronghold in Idlib province while Turkey, which sees Syrian Kurdish fighters as an existential threat, has been widening its military operations there to push them away from its borders.

The Britain-based Syrian Observatory for Human Rights said the airstrike hit a popular market in the rebel-held town of Maaret al-Numan, killing 13 civilians and wounding 18. The opposition-run Aleppo Media Center also put the death toll at 13 while the Syrian Civil Defense, a team of first responders known as White Helmets, said nine civilians, including two women, were killed.