I was visiting my grandmother this weekend, and she mentioned that her aunt and my great grandmother were there with some of their children. My great grandfather ran a local restaurant/dance hall in Laurium and a busing company that started as a tractor with a trailer that took miners to work.
According to my grandmother, it was not a very fancy party, but they had candy for kids, and the attendees were mostly Finns who were very poor. My great grandmother told her that someone shouted 'fire' twice, and that people didn't respond much to the first yell. When everyone did rush, my great grandmother and aunt told their kids to stay at the table,and they weren't involved in the crush at the bottom of the stairs.
My grandmother thought it was the mining company that orchestrated it.