Four people died Wednesday following an accident at the decommissioned Sullivan mine in Kimberley in southeastern B.C.
Word of the deaths came from the mine's owner, Vancouver-based Teck-Cominco, which has been doing reclamation work at the old mine site.
Company spokesman David Parker said the victims were not working underground at the time of the accident.
"We don't know what the cause was. That's what we're investigating, and we certainly don't want speculate at this point in time. So that's why we want to get there on the ground ourselves," he said.
Kimberley Mayor James Ogilvie said the four victims were rushed to the regional hospital in Cranbrook, which is about a 30-minute drive south of Kimberley.
Details are sketchy, but it appears that someone involved in the reclamation work called 911, reporting a person had succumbed to gas.
When the paramedics arrived, they were also overcome and suffered suspected cardiac arrest, said a government official.
Ogilvie said the local fire department was then called in to help.
"Our fire department responded to a call that was given to us by the B.C. Ambulance Service, requesting assistance up at the mine site. Our people went there and found there [were] at least four people in serious difficulty.
The problem occurred at a pumping station. Just exactly what has happened we don't know . . ."
The Sullivan mine was the world's largest lead-zinc mine from 1917 to 2001, when it was closed by Teck Cominco. Kimberley has a population of nearly 7,000, and has intensified its efforts to market itself as a tourist and retirement destination since the mine's closure.
with files from Canadian Press