There was some type of a misplaced ward and it had wound up killing her father. The letter didn’t say as much, since it was still a bit difficult to explain magic to her parents. Not only did receiving the letter about her father’s death devastate her. She knew that it was Dumbledore’s fault, that he had never placed them himself. For as much as he seemed to advocate for Muggleborns, he was practically a hypocrite.