The violence came as Turkey's President Erdogan announced that a Russian delegation would arrive the following day to resume talks aimed at easing tensions in the northwest Idlib region.
At least 19 civilians were killed in more than 155 air strikes targeting Idlib on Tuesday, according to the Syrian Observatory for Human Rights.
An air strike on the northwestern Syrian city of Idlib struck a school killing at least six including children.
Earlier Opposition forces in Syria captured the key village of al Nayrab in Idlib province from regime fighters.
It's seen as a setback for the regime, which has led an offensive targeting civilian infrastructure since December.
The violence came as Turkey's President Recep Tayyip Erdogan announced that a Russian delegation would arrive the following day to resume talks aimed at easing tensions in the northwest Idlib region.
The area is the country's last opposition-controlled stronghold and the regime's military campaign there, backed by Russia, has created a humanitarian catastrophe with nearly one million people displaced from their homes since December.
Most of them are now crowding areas close to the border with Turkey, living in camps, shelters, abandoned homes and in open fields. It is the largest single displacement of Syria's war, now in its ninth year.
Erdogan said no consensus was reached for a four-way meeting next month between the leaders of France, Germany, Russia and Turkey meant to address the crisis.
He added, however, that Russia's Vladimir Putin may still come to Turkey next week for a bilateral meeting.
Moscow has so far not confirmed a March 5 visit by the Russian president to Turkey.
Tensions have been running high between Turkey and Russia, which support opposing sides of the war in Syria.
The regime offensive has shattered a fragile ceasefire agreement that Turkey and Russia reached in 2018 and Turkey has threatened military action unless regime forces retreat to positions they held before the advance by the end of February.
"Russia supports Syria at the highest level," Erdogan told reporters before departing for a visit to Azerbaijan.
“Even if they deny it, we have evidence. We are forced to be in this fight.”
Turkish officials had reported small progress in two previous rounds of Turkey-Russia meetings but said the results were not satisfactory.
Turkey had set up a dozen observation posts as part of the 2018 agreement, many of which are now behind regime lines.
Ankara also sent thousands of additional troops into Idlib in recent weeks and has frequently engaged in military exchanges with regime troops.
According to defence ministry, 15 Turkish soldiers and a contractor were killed in February clashes during the regime's push on Idlib.
In the provincial capital of Idlib that carries the same name, a school was struck with a cluster bomb-filled rocket, killing two girls and a teacher, according to the Britain-based Syrian Observatory for Human Rights. Idlib-based opposition activist Hadi Abdullah confirmed that three people were killed in Idlib.
Another Idlib-based opposition activist, Taher al Omar, said the air strike also wounded 12 students and teachers.
The Observatory and Omar said the opposition captured the village of Nairab late Monday after intense fighting with regime forces that had captured the village earlier this month.
The village is close to the town of Saraqeb where two major highways in the country meet.
To the south of Nairab, regime troops captured two new villages raising to 10 the number of areas taken in the province since Monday, according to state media.
The capture of Maarat Tamater and Maarat Seen brings Assad's forces closer to Kafranbel, a major opposition-held town that gained attention in the early years of the Syrian conflict during weekly anti-regime protests because of humorous English-language banners carried by protesters.
The banners were initiated by anti-regime journalist Raed Fares who was shot dead in the town along with his friend Hammoud a Juneid in November 2018.