It's the deadliest mining disaster in Canada's history.
"No one will probably ever know what caused the explosion," said Monica Field, area manager for the Frank Slide Interpretive Centre.
"There was a Royal Commission of Inquiry, and also a Coroner's Inquest, as well as police investigations. They know that there was a methane gas fire and then a coal dust explosion, but what was the spark that ignited the methane gas has never been determined."
History states 237 men went into the mine that day, and only 48 came out alive. The mine disaster had a devastating impact on the town of about 1,000 people.
"A lot of these families had many children and when they lost their primary wage-earner, they were destitute. Some of them got compensation, but it didn't go a long way," said Field.
Brother killed in explosion
Alexander Petrie was the youngest miner to die in the explosion at the age of 17. His two brothers were also killed.
"He had only worked there two or three weeks, and they paid by the month. So, he didn't get a paycheque before he was killed," said Jean Schaffer, who only knows the three brothers through a family photo album.
She never got to meet her uncles. Schaffer's father also had a gruesome task that day.
"He was one of the men that brought the miners out and washed them and had them presentable for viewing ... for identification," Schaffer said.
Her parents didn't often talk about the disaster.
"It was traumatic," she said. "That mine has taken a lot from our family."
Many of the men were buried in two mass graves. It was the only way the community could deal with the scale of the disaster, according to local historian Belle Kovach.
"The bodies were in very, very tough shape, when they came out of the mine. So, after they had assembled body parts they wanted to bury them as quickly as possible," Kovach said.
The disaster prompted improvements to workers compensation and mine safety legislation.
"After this, every mine had it's own rescue team trained, ready with the self-contained breathing apparatus to get in there right away, because you don't have very long," Field said. "What happened here was terrible, ... terrible and tragic for the families, but the changes that were brought into mine safety really did save lives in the future."
A number of events are being held to mark the Hillcrest Mine Disaster 100th Anniversary in Crowsnest Pass, including a re-enactment of the funeral procession and a commemorative concert with James Keelaghan, Connie Kaldor and Tim Hus.
Schaffer will be attending the ceremonies to honour her uncles.
"I think I would have been very proud to have known them," she said.