en_tn/gen/34/27.md

the dead bodies

"the dead bodies of Hamor, Shechem, and their men"

plundered the city

"stole everything in the city that was valuable"

because the people had defiled their sister

Shechem alone had defiled Dinah, but Jacob's sons considered Shechem's entire family and everyone in the city responsible for this act.

had defiled

This means that Shechem had greatly dishonored and disgraced Dinah by forcing her to sleep with him. See how you translated "defiled" in Genesis 34:5.