Airstrikes by Damascus or its ally Moscow killed 12 civilians in a market in Syria's Idlib province, a monitor said Wednesday, as fierce fighting raged for the oppsition-held northwestern region.
Another 18 people were wounded when the warplanes hit the town of Maarat al-Numan around midnight (2100 GMT) on Tuesday, the Britain-based Syrian Observatory for Human Rights said.
The market was crowded with people out and about after breaking the daytime fast observed by Muslims during the holy month of Ramadan.
The strikes came as heavy clashes raged in the north of neighboring Hama province after the opposition launched a counterattack on Tuesday against pro-government forces in the town of Kafr Nabuda.
Fresh fighting on Wednesday took the death toll to 52 -- 29 troops and militia and 23 extremists, the Observatory said.
Naji al-Mustafa, a spokesman for armed factions, says the fighters regained control of Kfar Nabuda on Wednesday in an overnight counteroffensive, driving regime forces from areas they captured earlier this month.
Regime forces had seized Kfar Nabuda on May 8, cutting into rebel-held territory.
The clashes erupted on April 30, wrecking a cease-fire brokered by Russia and Turkey last September and raising fears of a wider regime offensive.
The last major rebel-held area in Syria, in the northwestern Idlib province and parts of neighboring Hama, is home to some 3 million people.
An extremist alliance led by Syria's former Al-Qaeda affiliate, Hayat Tahrir al-Sham, controls a large part of Idlib province as well as adjacent slivers of Aleppo, Hama, and Latakia provinces.
Russia and rebel ally Turkey inked the buffer zone deal in September to avert a regime offensive on the region which threatened humanitarian disaster for its three million residents.
Bashar al-Assad's regime has renewed its bombardment of the region since HTS took control in January.
Russia too has stepped up its airstrikes in recent weeks as Turkey proved unable to secure implementation of the truce deal.
The Observatory says more than 180 civilians have been killed in the flare-up since April 30, and the United Nations has said tens of thousands have fled their homes.