Why is this called Mehumah Gedolah? Also before, they were stricken with Techorim!
Mahari Kara: In addition to Mehumah Gedolah, they were stricken with Techorim.
Radak: It was in a covered place. This is worse than [above, when] it was in an exposed place. Malbim - an internal affliction is more severe. It was more severe in two other ways. (a) Fear and dread fell upon them. (b) Now, small and big were stricken.
Why did Hashem strike them harsher now?
Malbim: It is because they sent away the Aron. 1
Perhaps this is like Malbim said (verse 8), that they attributed their afflictions to chance and wanted to test if it will afflict people elsewhere. Why were Bnei Gas afflicted, and not the ones who sent it? Perhaps they should have protested against hosting the Aron, like Anshei Ekron did (verse 10). (PF)
What is the meaning of "va'Yisasru"?
Rashi: This is among words written with a Shin, for which there is a tradition to expound them as if they were written with a Samech.