. . . of rivets popping off the tank like machine gunfire as the Boston Molasses Disaster pursued its tragic course. It happened just after Noon on 15th January 1919, so lots of the witnesses were well familiar with the sound of machine gun fire from their experiences with the US American Expeditionary Force AEF in France.
What seems to have happened was that a massive (15m tall x 27m diameter) tank full of molasses ruptured and/or exploded. The latter is a likely probability because molasses inevitably fermented while in storage to produce carbon dioxide which may not have been properly vented. The gas pressure may have been exacerbated by the fact that the temperature had risen rapidly from -17oC to +5oC. But shoddy engineering (the tank was known to weep brown gook), insufficient testing, and absence of qualified inspection may have led to a catastrophic metal fatigue fracture than propagated until the rivets unzipped. The tank was almost full with an estimated 8700 cu.m of molasses which debouched in a 8m high wave travelling through the North End of Boston at nearly 60km/h. Several buildings were swept off their foundations and the elevated railway's supports were bent out of shape. In the dark tide 21 people and a lot of horses perished making it a little less lethal that the Great London Beer Flood which killed 1/3 as many people with about 1/6th the volume. The surviving residents took one of the earliest class-action suit against the company and eventually secured $600,000 compo. My sources don't say how much the lawyers took.
This continues the occasional series estimating the killing power in bangs/weight of various chemicals. From Botox to Sarin to propylene to molasses to carbon dioxide to dilute ethanol. These lethal doses range over 15 orders of magnitude from 150 ng to 150 tons. Choose your poison!