The pictures show a burn through of the nacelle cowl which kind of defeats the onboard extinguishers. Ths kind of continuous engine related fire has occured in the past when a torchlike burnthrough of the engine cases impinges on the nacelle wall and burns through the nacelle before the fire loop is energized. Shutting off the fuel is absoulutely necessary (once you figure out that something is burning) as well as the need for external help on the ground.