The two four-storey residential buildings that came down early on Wednesday morning contained eight families, state media reports, citing local officials.BBC rwported.
Several Moroccan news outlets report that the buildings - located in the south-westerly Al Massira suburb of the new part of the city - had shown signs of deterioration for several years. An investigation is now under way.
Fez, in north-eastern Morocco, is one of the North African nation's oldest cities, with parts dating back to the 8th Century, as well as being its third-most populous.
A search and rescue operation is ongoing to find anyone who may still be trapped under the rubble. Footage from the scene shows people and diggers sifting through the debris under the cover of darkness.
