This story is incredible on a number of levels. I mean, what's got me curious is what the heck was the neighbor doing with a pound of mercury in his shed? There's a lot of uses for the stuff, but nothing really home-hobbyish that I can think of. Not even back in the 60's hobbies, when grown men cheerfully splashed around in radioactive mail-order stuff.
Then there's the school response: quick, responsible and sane. Get everyone tested, get the worst of the folks who were exposed on (what I am assuming is) a treatment program to cleanse the stuff from your system, and wipe the bus from existence. I don't think it was anything too dramatic; probably a comptroller somewhere talked to a specialty place about the costs of decontamination while his finger ran down a line of asset devaluation on the bus fleet. Some quick math later, and that baby was headed for the crusher.
Of course, the fantasies are just priceless. The kid w/ the mercury is a hero! Due to his irresponsibly cool actions, people got sick and a bus was destroyed. You just made yourself the center of a school myth, dude.