Regime and Russian air strikes Saturday killed 15 civilians, more than half of them children, in northwestern Syria where ramped up attacks by the two allies have claimed hundreds of lives since April.
Idlib and parts of the neighbouring provinces of Aleppo, Hama and Latakia are under the control of Hayat Tahrir al-Sham, a jihadist group led by Syria's former Al-Qaeda affiliate. 
The region is supposed to be protected from a massive government offensive by a September buffer zone deal, but it has come under increasing bombardment by the regime and its Russian ally over the past three months. 
In the Idlib town of Ariha, seven children were among 11 civilians killed in Syrian air strikes that targeted two residential buildings and also wounded 28 other people, said the Syrian Observatory for Human Rights. 
One of the dead was a small boy who was found under the rubble by White Helmets rescuers, his face bloodied and his body covered in white dust, a photographer who works with AFP said from the scene.
He also witnessed rescuers digging through the rubble of a collapsed roof for more victims, while a member of the White Helmets moved the body of a young man into the back of a pickup truck.
Ariha made headlines after it was pummelled Wednesday by warplanes that claimed the lives of 10 civilians, according to the Observatory, when a picture of three sisters struggling for their lives went viral on social media networks.
The picture showed two dust-covered girls trapped in the rubble and clutching their baby sister by her shirt as she dangles from a bombed out building. 
One of the girls later died of her wounds while the other two are hospitalised and fighting to stay alive, according to local medics.
Russian air strikes on northern Hama province Saturday that hit an ambulance killed three rescuers while another child died in Syrian regime bombardment elsewhere in the Idlib region, the Observatory said.
Save the Children said on Thursday that the number of children killed in Idlib over the past four weeks had exceeded the number slain in the same region in the whole of last year.
Air strikes by the Syrian regime and its ally Russia on the Idlib region have claimed more than 740 lives since late April, according to the war monitor.
The UN says more than 400,000 people have been displaced. 
The UN Office for the Coordination of Humanitarian Affairs (OCHA) has documented 39 attacks against health facilities or medical workers in the area in three months.
At least 50 schools have been damaged by air strikes and shelling over the same period, it said. 
UN rights chief Michelle Bachelet on Friday condemned "international indifference" in the face of the mounting death toll in Idlib.
"These are civilian objects, and it seems highly unlikely, given the persistent pattern of such attacks, that they are all being hit by accident," Bachelet said.
"Intentional attacks against civilians are war crimes, and those who have ordered them or carried them out are criminally responsible for their actions," she said.
The region under attack is home to some three million people, nearly half of them already displaced from other parts of the country. 
The war in Syria has killed more than 370,000 people and displaced millions since it started in 2011 with a brutal crackdown on anti-government protests.