The Syrian regime and Russia have stepped up their deadly raids on the Idlib region since late April, despite an international deal intended to prevent a full-scale offensive on the area of some three million people.
Almost 730 civilians have been killed there in air strikes and ground-to-ground fire by the Damascus government and its allies in the same period.
The bombardment has also hit two dozen hospitals in the opposition area, which is made up of most of Idlib province as well as slivers of adjacent governorates.
On Wednesday, Russian air strikes killed 10 people from the same family, including three children, on a farm near the town of Khan Sheikhun in Idlib province, the Syrian Observatory for Human Rights said.
Ten others lost their lives in regime air strikes and artillery fire in other parts of the militant-run bastion, the Britain-based monitoring group said.
Among these, regime warplanes killed five civilians including two children in the town of Ariha in Idlib province, it said.
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A rescue worker in the town lifted the limp body of a toddler out of the rubble and rushed the child to an ambulance, according to footage shared by his White Helmets organisation.
His team members hurriedly worked through the debris and twisted sheets of corrugated iron, finding a young man on his back covered in grey dust - but still alive.
Also on Wednesday, opposition rocket fire killed two children in the northern regime-held city of Aleppo, state news agency SANA said.
According to the Observatory, rebel and militant fire from the Idlib region on adjacent government-held territory has killed 70 civilians since late April.
On Monday, air strikes killed at least 50 civilians in various parts of the bastion.
The Observatory said the majority were killed in Russian air raids on a busy market, but Moscow has denied any involvement.
The monitor, which relies on sources inside Syria, says it determines who carries out air strikes according to flight patterns, as well as aircraft and ammunition involved.
Mark Cutts, United Nations (UN) deputy regional humanitarian coordinator for the Syria crisis, this week described a worsening 'nightmare' unfolding in Idlib.
He said Monday's aerial onslaught was "one of the deadliest attacks on civilian areas that we have seen since the upsurge in fighting".
The Idlib region has since January been administered by Hayat Tahrir al-Sham - a group led by Syria's former al-Qaeda affiliate - but other militants and rebels are also present in the area bordering Turkey.
A September accord struck between Moscow and Ankara was supposed to set up a buffer zone around the region, but it was never fully implemented after militants refused to withdraw from that planned security cordon.
The recent violence has forced more than 330,000 people from their homes, the UN says, many seeking shelter further north in camps or olive groves along the Turkish border.
Syria's war has killed more than 370,000 people and displaced millions since it started in 2011 with a brutal crackdown on anti-government protests.
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