Six civilians were killed in a regime airstrike in the de-escalation zone in northwestern Syria on Monday, according to the White Helmets civil defense agency.
Three people were killed in the town of Maarat Al-Numan and three in the town of Hesh, Mustafa Haj Youssef, director of the White Helmets in Idlib, told Anadolu Agency.
Turkey and Russia agreed on last September to turn Idlib into a de-escalation zone where acts of aggression are expressly prohibited.
The Syrian regime and its allies, however, have consistently broken the terms of the cease-fire, launching frequent attacks inside the de-escalation zone.
The de-escalation zone is currently inhabited by about 4 million civilians, including hundreds of thousands of people displaced by the regime forces from cities and towns throughout the war-weary country in recent years.
Syria has been locked in a vicious civil war since early 2011, when the Bashar al-Assad regime cracked down on pro-democracy protests with unexpected ferocity.
Since then, hundreds of thousands of people have been killed and more than 10 million others displaced, according to UN officials.