Russian warplanes also wounded 100 people when they targeted a training camp of the Faylaq al-Sham faction in the Jabal Duwayli area in Idlib province.
Thirty-four Turkish troops have been killed in Syria since Thursday.
Reacting earlier to preliminary reports of the deaths, Kay Bailey Hutchison, the US ambassador to NATO, said the incident amounted to a 'huge change'.
Rebels control much of Idlib province and parts of the neighbouring Aleppo region that is home to some 3 million people — many of them displaced from other parts of Syria.
Jeffrey said an attack by Russian and Syrian forces, and the use of chemical weapons, would force huge refugee flows into southeastern Turkey or areas in Syria under Turkish control.
The draft resolution "condemns in the strongest terms the use of chemical weapons" in Syria.