At least 12 civilians were killed when the Assad regime and Russian assaults targeted Idlib, a de-escalation zone in northern Syria, local sources said on Tuesday.
Russian and regime fighter jets hit Idlib city center, Binnish town and Sahil Roj region, the White Helmets, a civil defense agency, said.
It also said four children were among nine fatalities in rocket attack hitting Idlib.
According to Syrian opposition groups' aircraft monitors, the attacks killed a civilian in Binnish.
Idlib is currently home to 4 million civilians, including hundreds of thousands displaced in recent years by regime forces throughout the war-torn country.
In recent months, nearly 1.7 million Syrians have moved near the Turkish border due to intense attacks by forces of the Assad regime and its allies.
In September 2018, Turkey and Russia agreed to turn Idlib into a de-escalation zone in which acts of aggression were expressly prohibited.
But since then, more than 1,800 civilians have been killed in airstrikes and shelling by the regime and its allies.
On Sunday, Turkey announced a new offensive, Operation Spring Shield, in northwestern Syria to protect civilians from regime attacks.
It came after at least 34 Turkish soldiers were martyred and dozens injured in a regime airstrike in Idlib on Feb. 27.