Fire?
Not being familiar with a 777, what would have caused that intense fire? Didn't look like the fuel tanks ruptured and started the fire. Does the 777 carry LOX near the main cabin area or is there just that much flammable material in the cabin?
Aluminium itself will burn quite happily once you've applied enough heat. Especially the thin stuff the skin is made of. That kind of fire can be quite common in scenarios like these.