Saline hydrides react with water violently to form the corresponding metal hydroxide, thereby liberating dihydrogen gas, e.g.,
These reactions are highly exothermic and H2. H2 thus evolved catches fire. The fire, thus produced cannot be extinguished by CO2. CO2, as it gets reduced by the hot metal hydride to form metal formate. To extinguish such type of fire, SAND can be used, since it is a highly stable solid.
NaH+CO2→HCOONa (sodium formate)