Russian-backed government forces step up attacks on rebel-held towns in northwest Syria, volunteer medic group says.

At least 22 civilians, including several children, have been killed in northwest Syria as Russian and government forces launched a series of air raids, according to volunteer medics who operate in rebel-held areas.

The Syrian Civil Defence, also known as the White Helmets, said the attacks on Tuesday targeted a dozen towns and villages in Maaret al-Numaan district, Idlib province, causing civilians to flee en masse towards internally displaced people (IDP) camps near the Turkish border.

Ahmed Sheikho, a spokesperson for the Civil Defence, told Al Jazeera that nine people were killed in the town of Tal Mannis, six were killed in Bidama and five others were killed in Maasaran. One person was killed in al-Kanayes, while another person was killed in Maar Shamshah, he added.

Among those who lost their lives in Bidama were a White Helmets volunteer’s wife and three children, Sheikho said.

A market in the rural town of Maasaran was also bombed, according to Sheikho, who said that dozens of people were wounded across the region in the attacks and that rescue operations were ongoing on Tuesday evening.

Russian and regime warplanes continue their mission to kill civilians in #Idlib. 12 people have been killed this morning so far, 6 of them from artillery shelling of a home in #Badama Town and other victims of airstrikes targeting those attempting to flee the bombings. pic.twitter.com/eGHK9WeiK5 — The White Helmets (@SyriaCivilDef) December 17, 2019

Videos posted on social media and confirmed by residents showed emergency crews pulling charred bodies along the debris-strewn streets of Maasaran as ambulances were arriving.

The bombing began at around 7am local time (05:00 GMT), Abbadeh Zakrah, a White Helmets volunteer based in Maaret al-Numaan district, told Al Jazeera.

“The sound of barrel bombs has not stopped all day,” he said. “Bombardment was targeting civilians fleeing from towns and villages near the main highway.

“This is a vicious and systematic bombing camping to force people out of the northern region,” Zakrah said.

Ongoing offensive

In April, Syrian government forces and their allies launched a ground and aerial offensive on northwest Syria, the last rebel-held territory in the country. More than 1,000 civilians have been killed in the hostilities, according to the United Nations, while hundreds of thousands more have been displaced since the escalation began.

Russia, which backs Syrian President Bashar al-Assad, and Turkey, a longtime supporter of opposition factions, cosponsored a de-escalation agreement for northwest Syria earlier this year that has since faltered.

Russian-backed forces have continued air raids on populated areas to wear down rebel groups that have, so far, repelled government attempts to seize back terrain.

Syrian government and Russian forces attacked two IDP camps on Monday, according to the White Helmets.

The Syrian troops on the offensive have recently captured rebel-held areas in the adjoining Hama province, as well as the town of Khan Sheikhoun in Idlib.

They are now seemingly pushing north, towards Maaret al-Numan, which sits on the M5 highway linking Damascus with the northern city of Aleppo.

The Syrian government has been battling to take control of the strategic highway, a move that would allow it to connect cities under its control and boost trade.

The region is home to nearly three million people, about half of whom were transferred there in large groups from other parts of the country that were retaken by pro-government forces.

The war in Syria has killed hundreds of thousands of people and displaced millions since it erupted in 2011 with the repression of anti-government protests.

Additional reporting by Farah Najjar