At the site of the strikes, an AFP correspondent saw a rescue worker carry the limp body of a tiny girl away from the rubble, her clothes blanketed in fine dust.
Bright red blood had gathered around her throat and, under a crop of dusty hair, her eyes were closed peacefully shut.
Another emergency worker stood with a body bag at his feet, as colleagues in white hard hats sprayed water onto a building partially pummelled to grey rubble.
Wednesday's strike was the second of its kind in less than a week, the Observatory said, after a Russian raid on the village of Jabala on Saturday also killed six civilians, including one child.
The monitor, which relies on sources inside Syria, says it determines who carries out an air strike according to flight patterns, as well as aircraft and the munitions involved.
The Idlib region, which is home to some three million people including many displaced by Syria's eight-year civil war, is controlled by the country's former Al-Qaeda affiliate.