A new cessation of hostilities agreement between Russia and Turkey, who support the opposite sides in the conflict, went into effect last week but violence has continued.
Regime air strikes on Syria's last major opposition bastion killed at least 15 civilians on Wednesday, striking bustling areas of Idlib city despite a fresh Russian-sponsored truce, witnesses and a war monitor said.
Several other civilians were wounded in the raids that hit a vegetable market and repair shops in Idlib, capital of the rebel-held province of the same name, said the Syrian opposition aircraft observatory.
The group said that Russian and the regime warplanes have targeted Idlib’s Maarat al Numan county and some villages while the British-based Syrian Observatory for Human Rights said the death toll was expected to rise from 15.
Yahya Abu al-Yaman, a volunteer with first responders the Syrian Civil Defense, said 15 people were killed and 65 were wounded in the strike. Most were in critical condition after warplanes struck a vegetable market and industrial area in Idlib city in the afternoon.
The bombardment charred several vehicles in the industrial zone, leaving torched corpses of motorists trapped inside, an AFP correspondent said.
One man was seen running towards the site of the attack, slapping his forehead with both hands in despair.
Mustafa, who runs a repair shop in the area, was lucky to escape with his life. He had just left the store to pick up some spare parts.
He said that he returned to find the shop destroyed and his four employees trapped under rubble. It was not immediately clear if they had survived.
"This is not the neighbourhood I left two minutes ago!" Mustafa said, tears rolling down his face.
Idlib has come under mounting bombardment in recent weeks, displacing tens of thousands of people in the northwestern province home to some three million.
A truce brokered this month by regime ally Russia and opposition backer Turkey was in principle to have taken effect from Sunday.
It follows a truce announced in late August, after strikes by the regime and its Russian allies killed some 1,000 civilians in four months, according to the Observatory.
The Syrian regime has repeatedly vowed to retake Idlib, which is run by Hayat Tahrir al Sham, a group dominated by Syria's former Al Qaeda affiliate.
Syria's war has killed more than 380,000 people, including over 115,000 civilians, since it broke out in 2011 with the brutal repression of anti-government protests.