Matthew Poole and continuators on Numbers 16:48

48 And he stood between the dead and the living , and the plague was stayed.

Whereby it may seem that this plague like that fire, Numb. 11. 1. began in the uttermost parts of the congregation, and so proceeded destroying one after another in an orderly manner, which gave Aaron occasion and direction so to place himself, as a Mediatour to God on their behalf.