Do you think some union lit the fire? You implied it. If not, I apologize.
The Triangle Shirtwaist Factory fire is literally burned into the souls of most NYers - just like 9/11 and the Slocum. It happened because the owners had locked the doors on the employees (on the 9th floor, I believe). Interestingly, one of the owners did it again in 1913 and was rearrested!
What I said was that I always heard that it was the union people who started the fire.