Carbon monoxide appears to have caused the deaths of five people in a home in the Yukon capital Sunday.
Fire Chief Clive Sparkes said that when firefighters entered the home they detected 10 times the amount of carbon monoxide needed to set off a detector.
"We checked all the victims for signs of life and found no signs of life with any of them. At that point the department set up some high-volume fans to ventilate the building, move fresh air in," he said.
Yukon Fire Marshall Dennis Berry said investigators are looking at the house's heating system, which included a wood-and-oil-fired heater.
The dead include 45-year-old Bradley Rusk, his 37-year-old wife Valerie, their 13-year-old son Gabriel, 11-year old daughter Rebekah and 47-year-old boarder Donald McNamee.
Coroner Sharon Hanley said investigators are trying to pin down the time of the deaths.
"Somebody had driven by and didn't see smoke in the chimney on Thursday, so it could be any time from Thursday night. We're looking more at maybe Friday that it happened," she said.
She said no autopsies will be done, but blood samples will be taken and sent to Vancouver for testing to determine if carbon monoxide was in the victims' systems.
Hanley said those results won't be known for a month.
The Rusk family had been living in Whitehorse for the past few years, although it had ties to Alberta.