Russia launched the strike on a market on a strategic rebel-held town, targeting militants and a weapons depot.
A Russian airstrike over a busy market in Idlib province in northwestern Syria killed at least nine people on Sunday. Russia is a top ally of Syrian President Bashar Assad.
Activists and UK-based opposition war monitor the Syrian Observatory for Human Rights said that Moscow launched the strike over the strategic rebel-held town of Jisr al-Shughur near the Turkish border.
Opposition-held northwestern Syria's civil defence organisation, known as the White Helmets, said over 30 people were wounded, and the death toll is expected to increase.
Farmers rushed the wounded to the hospital in bloodied vegetable trucks, while activists shared urgent calls for blood donations.
Neither Syria nor Russia commented on the airstrike, though Damascus says strikes in the northwest province target armed insurgent groups.
The Syrian pro-government newspaper Al-Watan, citing an unidentified security source, said that the airstrike targeted militants and a weapons depot.
Northwestern Syria is mostly held by the militant group Hayat Tahrir al Sham, as well as Turkish-backed forces.