The attack was the deadliest use of chemical weapons in Syria since 2013.
At least seven children died in rebel-held Idlib province.
The city is unrecognizable after half a decade of conflict.
The attacks are a further sign of Moscow’s broadening military effort in Syria.
The Russian Defence Ministry says Tuesday’s strikes targeted the Islamic State and other militant groups.
Syrian Democratic Forces freed more than 2,000 civilian hostages.
Bashar al-Assad’s forces encircled rebel-held parts of the last city last month.
This is how dire it has become.
“When thinking of Syria, think of the people there, not about ISIS or Assad.”
WASHINGTON (Reuters) - The United States said on Wednesday it had agreed with Russia to extend a cessation of hostilities