And those that died
muwth  (mooth)
causatively, to kill
in the plague
maggephah  (mag-gay-faw')
a pestilence; by analogy, defeat -- (be) plague(-d), slaughter, stroke.
were twenty
`esriym  (es-reem')
twenty; also (ordinal) twentieth -- (six-)score, twenty(-ieth).
and four
'arba`  (ar-bah')
four -- four.
'eleph  (eh'-lef)
hence (the ox's head being the first letter of the alphabet, and this eventually used as a numeral) a thousand -- thousand.