Airstrikes, likely to be Russian, on Thursday killed 22 civilians in a market in the northwestern province of Idlib, which is largely controlled by radical fighters, a monitor said.
The strikes hit the area of Harem, which is controlled by Hayat Tahrir Al-Sham, the Syrian Observatory for Human Rights said.
The Britain-based monitor says it identifies who carried out airstrikes based on flight patterns, munitions used, and aircraft.
Meanwhile, Syrian opposition fighters have released 13 of their prisoners to the regime.
The men, who identified themselves to the media as soldiers and civilians attached to the Syrian Army, who were captured by opposition fighters in the battle for Harasta, cried in relief.
They thanked God, the Syrian Army, and President Bashar Assad for their freedom.
Hezbollah’s Al-Manar TV said the regime released five “terrorists” in exchange.