Ten civilians, including women and children, were killed and dozens others were injured when Russian and Syrian warplanes launched several airstrikes after Friday's prayers on Idlib and Jericho.
Local sources said that the death toll is expected to increase.
Rescue teams are still working to recover the victims and the wounded, sources added.
Earlier, the Syrian Observatory for Human Rights said that a series of air strikes struck a military airport in northwestern Syria on Thursday, killing 16 jihadists including a top fighter from Al-Nusra Front.
SOHR added that more than 60 air raids targeted the Abu Duhur military airport in Idlib province which Al-Nusra and allied Islamist fighters seized in September.
Observatory director Rami Abdel Rahman said however that it was unclear if the strikes were carried out by the Syrian regime, Russian or US-led coalition aircraft.