The recommendation for EVs in a fire situation is to soak with water directly on the pack. Yes, it can liberate hydrogen and hydroflouric acid, but 'not' soaking with water isn't going to stop that, whereas if you do throw water on then at least it 'might' keep some of the battery cool and maybe stop the whole pack from going up as each cell sets the next one on 'fire'.
It is not really a 'fire', what is happening is the lithium is reacting directly with the oxygen in the electrode materials. Rather than share the oxygen with the transition metals in the electrodes, lithium is selfish and would prefer to have it all for itself. But keep it at the right temperate and electrical conditions and it is metastable in that electrode composition. Change the temperature and/or electrical potentials and it'll seize the oxygen directly given a chance.