At least 15 people, including a number of children, were killed by Russian airstrikes in an opposition-held part of northern Syria, a local civil defense source said Monday.

Two consecutive raids by Russian warplanes that targeted the town of Abu al-Duhur in the Idlib province left another 30 injured, Ahmed Mustafa told Anadolu Agency.

Russian warplanes continue to indiscriminately target opposition controlled hospitals, marketplaces and civilian areas along with fighters' facilities since September 2015.

Syria has been locked in a vicious civil war since early 2011, when the Assad regime cracked down on pro-democracy protests -- which erupted as part of the "Arab Spring" uprisings -- with unexpected ferocity.

Since then, more than a quarter of a million people have been killed and more than 10 million displaced across the war-battered country, according to the UN.