I witnessed a death at WDW today (presumably - it's not in the news yet).
It was in Town Square on a sidewalk, and appeared to be a collapse for medical reasons. I'm not a medical doctor, but I wouldn't be surprised if it turned out to be caused by a sudden health problem (stroke, heart attack, aneurism, embolism, etc).
I watched much of it happen. The firefighter who administered the AED (onstage) was part of my party visiting that day, so we know there was no pulse and essentially no hope as they took the person backstage. While I haven't seen confirmation in the news of a death, it will shock my firefighter friend if this person was somehow revived (she was without a pulse for some minutes, including as they took her away).