At least ten civilians were killed and 34 others injured by regime artillery shelling on residential areas in the country's northwestern Idlib province in the past 24 hours, according to the White Helmets civil defense agency on Sunday.  

The shelling targeted 13 populated areas in the towns of Khan Shaykhoun and Marra al-Numan in Idlib's countryside, the White Helmets said.  

Three children and four women were among those killed in the attacks, it added.  

Speaking to Anadolu Agency, White Helmets director in Idlib Mustapha Haj Yousuf warned of a "humanitarian catastrophe" over the ongoing regime attacks.  

"Too much blood has been shed in the past period," he said, adding that most of the victims were children and women.  

Regime attacks in the de-escalation zone of Idlib are estimated to have killed at least 63 civilians and injured hundreds since the start of this year.  

Syria has only just begun to emerge from a devastating conflict that began in 2011, when the Assad regime cracked down on demonstrators with unexpected ferocity.