Separately, a civilian support worker with the Turkish military was killed in a car bomb blast in the same province.
At least 15 people were killed on Tuesday when suspected Russian warplanes struck a crowded market in the opposition-held city of Ariha in the second such strike on a shopping area in opposition-held Idlib within 24 hours, residents and rescuers said.
They said the aircraft was flying at high altitude, which differentiates it from the ageing Syrian air force.
The opposition-run White Helmets or Civil Defence service said a further 20 people were wounded in the strike. Video released by local activists showed extensive damage, with produce mixed up with human parts.
Reuters could not verify the authenticity of the footage
A resident said the attack took place at the busiest time of the day.
Russia's defence ministry regularly says it is attacking militants. It denies opposition and witness accounts that its warplanes target market places, medical centres and residential areas away from frontlines.
Syrian media made no mention of the strikes.
Civil Defence workers and residents said dozens of raids have since Sunday struck the towns of Khan Sheikhoun, Maarat al Numan, Saraqeb and scores of villages.
On Monday, warplanes bombed a potato market in nearby Saraqeb, killing at least 11 people, mostly farmers and traders. Shortly after, warplanes knocked out of action the only public hospital in the city, which was supported by French charity Medecins Sans Frontieres (MSF).
MSF said in a statement the attack on the hospital killed at least five people, including a child, and injured six. It said this was the second strike on the hospital in just over a week.
Russia has escalated its strikes in Idlib in recent months, throwing its military weight behind a Syrian military campaign to push deeper into the mainly opposition-held northwestern province.
Turkish support worker killed
A civilian support worker for the Turkish Armed Forces was killed in a car bomb attack on a military convoy in Idlib, the Turkish General Staff said Tuesday.
In a statement, the military said terrorists detonated a vehicle while a Turkish military convoy deployed in Idlib as part of an international agreement to establish de-escalation zones was passing through.
The statement also said a Turkish soldier and another civilian worker were injured in the explosion.
The military also offered its condolences to the civilian's family and wished a speedy recovery to the wounded.
On his Twitter account, Turkish Forestry and Water Minister Veysel Eroglu said the civilian worked at the ministry.
“Today, a member of the General Directorate of State Hydraulic Works, Yasin Tanboga, who joined Operation Olive Branch, was martyred. Mahmut Pakyurek was seriously injured and specialised sergeant Omer Gunes was injured slightly.”
The deployment in the northwestern region was launched last October under a deal reached with Russia and Iran during the Syrian peace talks in the Kazakh capital Astana.
The establishment of de-escalation zones was agreed to in May between Turkey, which backs groups opposed to Bashar al Assad regime, and Russia and Iran, who support the regime.