I was watching my fiance run and someone died literally right in front of me at the Brooklyn half-marathon in the fall (he was a young guy - I'd say late 20s). He collapsed right at the finish line and they couldn't revive him. The crazy thing is there was no mention of it after the race or anywhere, I tried googling to find out more info. but nothing. The only info. I found was on /r/running people where people who were also in attendance were talking about it. Marathons just seem so unnatural to me.

> I've seen people die running a half marathon.

From the "Those who don't learn History are doomed to repeat it" department: the whole reason people "run a Marathon" is because of the legend of a Soldier, Pheidippides, running from Marathon to Athens and dying after announcing victory in battle.

If people are aware of this basic information and still are stupid enough to run without any preparation, I'd say they would be candidates for the Darwin Awards.

Actually seen firsthand, or read about it having happened? (These are very different, because they imply much different prevalence.)

The author of the article records a short clip describing how he's feeling at each waypoint, and doesn't seem to have pushed himself terribly hard.

I think you have to think about how those people died. Heat exhaustion? An underlying heart condition? I don't think they died of not having enough nutrients, or not eating soon enough before running.