Syria Civil Defence, a rescue service known as the White Helmets, are continuing rescue operations in Tabeesh village and reported on social media that fierce bombings killed at least seven people.
Syrian regime forces targeted opposition-held areas of southern Idlib province and rural Damascus on Tuesday, British-based war monitor, the Syrian Observatory for Human Rights (SOHR), reported.
Russian-backed regime forces launched an offensive in late 2017 against opposition and allied groups in Idlib.
Fighting raged in the province, where a regime offensive helped by Iran-backed militia, has gathered pace in the last two weeks.
Syria Civil Defence, a rescue service known as the White Helmets, continued rescue operations in Tabeesh village and reported on social media fierce bombing killed at least seven civilians, including six children and a woman.
moments from the horrific massacre committed by Russian warplanes after 3 airstrikes targeted #Tabesh village, southern #Idlib countryside. Left behind 7 civilians killed including ,6 children and woman. pic.twitter.com/TXdpNX1kG7— The White Helmets (@SyriaCivilDef) January 16, 2018
Videos uploaded to social media show dark clouds of smoke rising above a mosque and other destroyed buildings in what is purported to be the village of Arbeen with military planes flying overhead.
SOHR reported warplanes and helicopters also targeted areas in the southern countryside of Idlib province in the morning causing great material damage and leaving many people wounded.
Idlib province is the biggest chunk of Syria still held by opposition groups fighting Syrian regime leader Bashar al Assad, with a population swollen by Syrians who have fled regime advances in other parts of the country.
Assad has defeated opposition forces in many parts of western Syria with critical help from Russia and Iran.
Displacement amid escalating violence
Escalating violence in northwest Syria has caused more than 200,000 displacements since mid-December, the UN said on Tuesday, warning that medical facilities in the area were struggling to cope.
In a new situation report published Tuesday, the UN's humanitarian coordination branch (OCHA) said it had recorded 212,140 instances of displacement between December 15 and January 16.
The largest displacement, 58,338 people, was to the village of Dana in Idlib province, but other waves of civilians fled to areas in the adjacent provinces of Aleppo and Hama.
In a first, OCHA said, around 6,700 families fled opposition-held areas of Hama province to nearby regime-controlled territory.
Idlib and slivers of the neighbouring provinces are now hosting more than 1.1 million internally displaced Syrians, according to the UN.
'Running low' on medical supplies
As hostilities between regime forces and anti-regime forces escalate, OCHA said it had received reports of several health clinics in the area being rendered out of service in the bombardment.
Other facilities, it warned, were "running low" on medical supplies.
"Facilities are strained due to the increasing caseload because of the recent displacement," the situation report said.
"The low winter temperatures and the lack of shelter is exacerbating the health situation of the IDPs (internally displaced people) causing winter-related illnesses."
According to Syrian Centre for Policy Research, more than 470,000 people have been killed in the Syrian war.