I had the Mission Kidnapping at Sanctuary Hills. I had to go for Medford Memorial Hospital what was defended by a lot of Super Mutants. I found the hostage, but she was dead. Why?

What did I do wrong? Perhaps I was too careful or too slowly?

you killed her..you animal!

most likely stray bullets, or explosives

i suggest just pay the ransom 200-500 caps ain't so bad

This is absolutely not possible! I use a sniper rifle with silencer and no grenades were used neither by me nor by Super Mutants.

Did you have a companion with you? May be he /she used a grenade.

If you travel into certain parts of the Hospital, the Supermutants in the area where the Hostage is held will use Grenades to try and kill You through the Floor.

This. AI's not too bright.