Airstrikes by unidentified aircrafts targeted the town of Sieger in the countryside of Idlib, leaving two women and two children among those killed, said the Syrian Observatory for Human Rights, Xinhua reported.
The death toll could likely rise as 25 people are suffering critical wounds.
Idlib, much of which is controlled by an array of jihadi groups, has been under intensified airstrikes over the past couple of days.
The rebels accused Russia of being behind the first airstrike that killed 23 people on Tuesday, a claim later denied by Moscow.
Reports said the airstrikes could be a prelude to a wide-scale military offensive in Idlib between the Syrian army and the rebels there.