Seeking sources

[rhu]

I've been asked to give the dvar Torah next week (parshat Korach). I'm struck by one word in the description of the earth swallowing the conspirators, but haven't found any commentary about it:

וַיֵּרְדוּ הֵם וְכָל-אֲשֶׁר לָהֶם, חַיִּים--שְׁאֹלָה; וַתְּכַס עֲלֵיהֶם הָאָרֶץ, וַיֹּאבְדוּ מִתּוֹךְ הַקָּהָל.

So they, and all that appertained to them, went down alive into the pit; and the earth closed upon them, and they perished from among the assembly. (JPS translation)

I'm wondering why the text specifies that they descended alive into the pit. My Mikrot Gedolot had nothing on this word. Anyone have other sources?