Kam tells me that in Spanish, firefighters are "los bomberos"; turns out that "bomba" means both "bomb" and "pump."
The similarity of the two words made me wonder if they might be related in English, even though I know that etymology by sound is not sound etymology. So I looked them up.
It turns out that English "pump" may actually derive, distantly, from Spanish "bomba," but my dictionaries are unclear on whether that's related to the Italian "bomba" that's the root for English "bomb." So it's possible that Spanish "bomba" is actually two etymologically distinct words--a Spanish homomorph.
Interestingly, both Spanish "bomba" meaning "pump" and Greek "bombos" (the source of Italian "bomba" meaning "bomb") are, according to MW3, "of imitative origin"; I guess bombs and pumps both can sound a little like the word "bomba."