From the time of the earliest permanent playhouses in the United States until the early 20th century, theatre fires were a continual danger. Mostly due to dangerous gas lighting and highly flammable materials used in theatrical production, there were well over a hundred major theatre fires between the first serious one at Boston's Federal Street Theatre in 1798 and a tragedy at the Brooklyn Theatre in 1876 during a performance of The Two Orphans when 197 people were killed. The greatest disaster occurred on 30 December 1903 when Chicago's Iroquois Theatre burned during a performance of the musical Mr. Bluebeard starring Eddie Foy. Despite Foy's heroic efforts to calm the audience, over 600 people were killed. The tragedy was also a public relations disaster for the Theatrical Syndicate. It led to the end of gas-lit theatres and to newly stringent laws mandating safety exits from theatres and other precautions.
The Historical Dictionary of the American Theater. James Fisher.