The fire broke out just before 11:10 at an apartment at Brookfield Grove in Kimmage.
Witnesses reported hearing an explosion and coughing coming from inside the property, and one man has been taken to hospital.
Dublin Fire Brigade says the blaze has been brought under control and the Gardaí, ESB Networks and Bord Gais have all been notified.
Units from D/barn, D/brooke, N/grove are responding to reports of smoke issuing and persons reported from an apartment in Kimmage— Dublin Fire Brigade (@DubFireBrigade) April 30, 2018
3 pumps are dealing with the fire in Kimmage with 1 casualty being treated— Dublin Fire Brigade (@DubFireBrigade) April 30, 2018