I was north of the 844 when this happened, I think near the turntable. It was a bit "exciting" at the time, as those of us familiar with the machinery knew immediately that "something's not quite right." Lynn did yoeman duty as well as having exceptional presence of mind staying in the cab long enough to shut things down, and yes he did get a slight burn from the escaping wet steam, but was back on duty right after, as Hotwater noted.
At the time there was a big debate over the cause; either over rolling or bad tube material. I never did hear the conclusion-or if I did, I've forgotten--that was quite a while ago!