Every year the firemen of Gillingham, in Kent, England, would construct a makeshift house out of wood and canvas for the popular fire-fighting demonstration at the fundraiser for St. Bartholomew’s Hospital.

As part of the festivities, several local boys would typically be selected to help out by playing the parts of members of a wedding party. Dressed in costume, the boys climbed to the third floor of the house and remained there while a smoke fire on the first floor created the illusion of an emergency.

On July 11, 1929, nine boys – aged 10 to 14 – and six firemen waited on the top floor, awaiting rescue, when the fake fire suddenly developed into the real thing. An actual emergency broke out, but spectators assumed they were witnessing some very convincing acting, so they did nothing to prevent the ensuring tragedy.

While the inhabitants of the house screamed and yelled for help, spectators cheered and clapped, assuming the burning bodies were merely dummies.

All 15 people inside the house died.

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