Areas hit included a market, and at least five children were among those killed, the British-based Observatory said. It said the death toll was expected to rise because of the number of people seriously wounded. Idlib is in rebel-controlled territory.
Men try to put out a fire at a market hit by air strikes in Idlib city, Syria
Air strikes carried out by Syrian or Russian warplanes killed more than 20 people in the northwestern city of Idlib on Sunday, monitoring group the Syrian Observatory for Human Rights reported.