No casualties have been reported since the fire broke out on the top floor of a building on Leningradsky Shosse, and spread to the rest of the building, a source in the firefighting service said.
Firefighters fear a natural gas explosion may occur.
"Firefighters can smell a strong gas smell at the entrance, where flats are on fire. An emergency brigade of Mosgaz [the city's gas distributor] has been called to the scene," he said.
Five firefighting units are currently battling the blaze, and evacuating residents.