Adam Clarke on 1 Samuel 5:12

The men that died not - Some it seems were smitten with instant death; others with the haemorrhoids, and there was a universal consternation; and the cry of the city went up to heaven - it was an exceeding great cry.

It does not appear that the Philistines had any correct knowledge of the nature of Jehovah, though they seemed to acknowledge his supremacy. They imagined that every country, district, mountain, and valley, had its peculiar deity; who, in its place, was supreme over all others. They thought therefore to appease Jehovah by sending him back his ark or shrine: and, in order to be redeemed from their plagues, they send golden mice and emerods as telesms, probably made under some particular configurations of the planets. See at the end of 1Sam 6:21 (note).