As a northern British Columbia community works to recover from a shattering explosion which ripped through a local sawmill, speculation has already begun on just what caused the blast.
Nineteen people were injured as flames ate away at the Babine Forest Products sawmill in Burns Lake, B.C., and two remained unaccounted for Saturday.
RCMP and fire officials have not offered details on what could have sparked what has been described as a "fireball" ripping through the facility, but eyewitnesses say they heard a massive "boom." And those who've spoken to recovering victims say employees reported the smell of gas at the mill before the explosion.
Welder Bruce Disher, who has worked at the mill for 31 years, said safety has always been top-of-mind at the facility.
"I know the mill's been having a lot of problems with freeze-up and stuff. Of course the weather here was 40 below for a couple days," he said.
Disher said workers had been using a type of propane torch to thaw ice.
But he added "if there's any inkling of any gas problems, it's evacuated and we check it out thoroughly before anything happens
An expert on sawmills cautioned that while the facilities certainly are packed with plenty of tinder, roaring fires at modern-day sawmills aren't all that common.
"My experience has been that they're extremely careful, so bad fires at mills, I believe, are less frequent than they were," said Hugh Davies, a professor at the University of British Columbia who is part of a research program studying the safety of sawmill workers.
"There's no reason to think that this would be more likely in a sawmill. But once the fire gets going, then of course you've got all the fuel there, all the wood that's being manufactured, the building itself, the dust."
The now burnt-out mill is a joint venture with the Burns Lake Native Development Corp. — made up of six bands — and Portland, Ore.-based forest products company Hampton Affiliates.
It appears the explosion and subsequent fire at the facility isn't the first blaze to hit the mill. An online news story from the Lakes District News noted a different fire on March 1, 2011 shut the mill for some time. A spokesman for the mill had said an electrical failure was to blame and described the fire as "significant," but noted there were no injuries.
Donna Freeman, spokeswoman for WorkSafe BC., said the agency has officers on the scene in Burns Lake, but she said they're just gathering information at this point.
Part of the investigation will be to look at the prior safety record of mill.
"Probably over the weekend, our officers will be pulling the safety history," she said.
Davies said smaller fires are not uncommon at sawmills, but bigger, roaring blazes, like the one which ravaged the mill Friday night — particularly if it did turn out to be caused by a gas leak — are far less frequent.
There are possible scenarios in which a gas explosion could occur at such a facility, though, Davies said.
Natural gas is used in most sawmills to dry wood in giant kilns, he noted. If that practice was carried out in the Burns Lake mill, it is possible that a natural gas leak could have triggered an explosion.
The same natural gas, if it was used to heat the mill's tightly enclosed buildings, could also contribute to the possibility of an explosion if a leak had somehow occurred.
Disher said mills can be dangerous.
"There are natural gas pipes running and there is propane and there is diesel and there is hydrolic oil and they're all flammable. From being a welder I know this," he said.
"But we have people that are there for that reason (for safety precautions)... I don't believe there was any negligence at all."
There has also been comment in the community on the type of gas suspected of triggering the explosion. A chief at a Burns Lake community centre said he'd heard workers say there might have been a propane gas leak in the mill's basement.
Davies speculated propane could have been used as a vehicle fuel for fork-lifts or other transportation equipment at the mill. He said the mill could have had a large tank to store propane if it was being used on a regular basis.
"You're not going to want people running out to get propane at Prince George every other day so you'd probably have it delivered," he said.
Davies added, however, that modern sawmills typically take very strict precautions to prevent fires because of how fast a blaze can spread should one be sparked.
"They're extraordinarily careful," he said, adding that even a welder working on something in a sawmill would have an employee designated to watch for sparks that need to be extinguished.
Davies said over-exertion, or being struck by an object are far more likely risks from working at a sawmill than a fire, particularly a large explosion.
Kay Teschke, another UBC professor who has studied safety practices at sawmills, said British Columbia in particular, has been at the forefront of safety improvements at the facilities.
"B.C. has been a leader in the sawmill industry," she said. "I think that fires at sawmills are now quite rare."
Teschke said mills have special clean-up systems to automatically clear away sawdust from inside the mill, which helps reduce the fire risk.
Chief Albert Gerow, chief of the Burns Lake band and president of the Burns Lake Native Development Corporation, which also has a stake in the mill, was shaken by the incident.
"The reality of what had happened really sunk in. The sawmill is completely demolished" he said from the town.
"It has a huge economic impact on our community. There would be a strong desire to have it rebuilt."
Steve Zika, a spokesman for Portland, Ore.,-based Hampton Affiliates, a co-owner in the mill, flew to Burns Lake on Saturday. He said a decision hasn't yet been made on whether to rebuild the mill, though the preference would be to do so.