Russia launched another night of airstrikes across Syria's northern province of Idlib on Sunday.
Rescue workers in the town of Kafr Nubl rushed to put out fires and dig through rubble in the search for survivors.
In the provincial capital Idlib city, one witness said a five-storey building was leveled and at least 15 people were feared dead.
Several other deaths and dozens of injuries have been reported across the province.
In the city of Maarat al Numan, civil defense workers rushed babies and other patients out of a damaged hospital.
In December, the Syrian army, backed by Iranian militia and Russian airpower, launched a major offensive to retake Idlib. It's Syria's last and most-densely populated province still mainly under opposition control.
Russian jets have intensified their strikes on rebel-held Idlib after Syrian militia shot down a Russian warplane on Saturday and killed its pilot.
Russia's Defense MInistry says it is targeting Islamist militants, not civilians.