RCMP Const. Lesley Smith said Tuesday officers plan to speak to everyone who worked at the mill about the day of the disaster and the days leading up to it.
"Witnesses have been coming forward with concerns they've had in the past and those are being brought forward not only to RCMP investigators, but also to the WorkSafe BC investigator," said Smith. "All that information is pertinent in finding out what the cause of this explosion was."
The mill was destroyed Friday night, injuring 19, some critically, and leaving about 250 people jobless.
Survivors recall seeing a flash and a fireball, and rescuers recall that some of their colleagues, suffering burns from the blaze, were forced to jump from the building's second storey.
Relatives confirm two First Nations men, Carl Charlie and Robert Luggi, were missing after the explosion. On Monday, the BC Coroners Service confirmed the remains of two people had been found within the charred debris of the mill.
During an interview after the blaze, Bruce Disher, a welder of some 31 years, said several days of exceptionally cold weather meant workers were forced to thaw pipes with torches and that some of those pipes contained different gasses.
Survivor Vinh Nguyen also said he was concerned about the buildup of sawdust in the mill and mentioned he was "on edge" because he had to put out a fire only two weeks earlier with fire extinguishers and a garden hose.
Other workers reported smelling gas before the explosion.
Experts say small fires in mills happen sometimes, but huge fires like the one in Burns Lake are incredibly rare. B.C. generally has a good safety record in sawmills, they said.
Al Gerow, chief of the Burns Lake Band and president of the Burns Lake Native Development Corporation which has a business stake in the mill, said Tuesday the mood in the community is sombre and many are angry.
Gerow, who also sits as a director on the mill's board, said workers attended a meeting Monday with Hampton Affiliates, the Oregon-based company that is the majority owner of the mill.
"Probably the single largest question was why, and we won't know that until naturally the investigators are finished their work," said Gerow.
When asked about the sawmill's safety record, Gerow said he worked as an assistant human-resources manager at the mill in 2000 and said employees strived to keep their workplace safe.
Wilf Adam, chief of the Babine Lake Nation, said people are becoming angry and upset with the way the mill was run, adding he's heard concerns from workers that there was no safety committee.
"If you have more than 200 employees in a dangerous working environment, there should be some kind of a committee," he said.
Two of his band members are in hospital in Vancouver with severe burns. One of them was due to have surgery Tuesday.
Another member was flown to hospital in Edmonton where he is able to sit up and speak with family, Adam said.
Steve Hunt, western director for the United Steelworkers, said he won't speculate on any safety concerns or causes of the disaster and has asked others not to speculate, either.
"I learned a long time ago when you're investigating serious incidents like this, you're best to wait for the investigation before you make announcements of what your theory is of what may have happened," he said.
"I'm content to wait and will be involved in the investigation obviously and if there were problems we'll expose them."
Hunt said the anger in the community is borne from the state of mourning people are in. He said people are confused, angry and fearful and are "lashing out."
Concerns about safety and are being passed on to investigators with agencies such as WorkSafeBC and the B.C. Safety Authority, said Smith.
Those agencies have said past safety audits of the mill are subject to privacy laws and can't be released until they've been vetted to ensure they are scrubbed of anything that might violate those laws.
The mill's CEO Steve Zika told workers Monday night that reconstruction could take at least 18 months and a final decision on whether to rebuild may depend on whether it can obtain a secure timber supply.
Provincial officials also assured the gathering that several ministries are now working to fasttrack a timber supply pact and also find transition funding for laid-off employees.