"In 1919, a tank of molasses in Boston collapsed. Molasses is thick, so you might think it would flow out slowly, but it didn't. The wave of molasses swept down the streets too fast to outrun, demolishing buildings and killing 21 people."<p>From (<a href="https://what-if.xkcd.com/111/" rel="nofollow">https://what-if.xkcd.com/111/</a>), where I originally learned about this event :P
And from the "plus ça change" department - the company that owned the tank tried to avoid responsibility by claiming that it had been blown up by anarchists.
This line from the Wikipedia article is worthy of Bulwer-Lytton consideration:<p><i>Others had debris hurled at them from the rush of sweet-smelling air.</i>