At least 72 people, among them 20 children, were killed in Tuesday’s attack in rebel-held Khan Sheikhun.
Syria has been accused of killing at least 95 civilians and destroying hundreds of houses in Idlib, in a last-minute dash before the ceasefire was called.
For ordinary Syrians cornered by the regime’s brutal crackdown, an escape across the border into Turkey is their only chance of survival.