[EngineDad]

I spent most of my adult life sailing on RO-ROs (Roll on -Roll off) otherwise called Car Carriers. Most as a Chief Engineer. The worse part of trying to fight a fire in the cargo hold is that usually there are no fire lanes or clear paths for the fire fighters to traverse. Every inch is used for cargo and the space between the cars is filled with lashing gear which is a tripping hazard. Combine that with heavy black smoke and you are in the dark barely able to move.

Generally, these spaces are protected with either Low Pressure CO2 or in some cases a foam smothering system. My guess here is a CO2 system that wasn't used or effective because there were no boundaries keeping the CO2 in the space because cargo hold water-tight doors were open- or the ship was ventilating the holds to remove smoke/heat to be able to see. Just a guess.

[New Perspective]

You make some excellent points and unfortunately they were deadly to some brave men. Access to extinguish ignition points is not as easy as breaking a window or cutting a hole in a roof. It is a very different beast. Thank you for sharing your knowledge.