Dozens more civilians were injured in the strikes, including some who were in serious condition, the Britain- based Syrian Observatory for Human Rights said.
"Residents were fleeing the village of Al-Tukhar in Aleppo province when the strikes hit," said Observatory director Rami Abdel Rahman.
He said the strikes appeared to have been carried out in error, with the civilians being mistaken for IS fighters.
The Observatory -- which relies on a network of sources inside Syria for its information -- says it determines what planes carried out raids according to their type, location, flight patterns and the munitions involved.
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Al-Tukhar lies 14 kilometres (nine miles) north of the town of Manbij, a key stronghold of IS in Aleppo province.
The Syrian Democratic Forces, an alliance of Kurdish and Arab fighters that is backed by the coalition, broke into the western districts of Manbij in late June.
But their advance has been slowed in the past month because of landmines planted by the jihadists, who have also launched suicide attacks against the SDF.
The Observatory yesterday had reported at least 21 civilians dead in US-led coalition strikes on Al-Tukhar and Manbij.