Investigators say they cannot confirm how many victims might be in the charred house near Chilliwack, east of Vancouver, or at a second crime scene in Langley, where at least one person was found dead.
They believe the dead are all from one family and the suspect is among them.
Vancouver media have published copies of a Facebook post from a man, identified as Randy Janzen, confessing to the murder of his daughter, wife and sister. The Vancouver Province posted the message in its entirety.
It begins by saying: "Over the last 10 days I have done some of the worst things I could have ever imagined a person doing."
The post goes on to detail how his daughter, Emily, had suffered since elementary school from migraines that made her "very ill" and had pushed her into a severe depression.
"I took a gun and shot her in the head and now she is migraine-free and floating in the clouds on a sunny afternoon, her long beautiful brown hair flowing in the breeze, a true angel," the post says.
The post says the man shot his wife "because a mother should never have to hear the news her baby has died" and, "a couple of days later," killed his sister "because I did not want her to have to live with this shame I have caused all alone."
"Now my family is pain free and in heaven," he concludes. "I have great remorse for my actions and feel like the dirt that I am."
He signs the post "Love Daddio."
Police said they are aware of the Facebook message and it is part of their investigation.
The burned out house sits on a quiet suburban street of large family homes and beautiful lawns with mountains in the distance. All that remained Friday was a scorched shell with the roof mostly collapsed.
Neighbours said there was a standoff at the home Thursday night before a fire.
Rudy Trouwborst, who lives on the same block in Rosedale near Chilliwack, said police arrived and told her to stay indoors.
"They said, 'Go inside. It's very serious,'" she said.
She said she then heard what sounded like four or five gunshots before the home caught fire.
Sgt. Stephanie Ashton said an emergency response team used distraction devices to try to make contact with someone believed to be in the house.
Amanda Blanchard, who has a view of the scene from her home five minutes away, said she noticed a commotion from her deck sometime after 6 p.m.
"It was a huge ball of smoke," Blanchard said. "We were like, 'OK, this isn't anything small. This is quite serious.'"
Neighbour Lucy Vandermeer said she thinks the home exploded.
"It was quite the bang. It looked like a gas fire to me," she said.
The telephone listing for the address is R and L Janzen.
Trouwborst said a couple and a child lived in the house, but she didn't know them. Vandermeer said "they stayed to themselves."
The Chilliwack School of Performing Arts posted a memorial to Emily Janzen on Facebook calling her an "incomparable" former student and instructor.
Kim Mallory, a photographer based in Chilliwack, took portraits of Emily Janzen in the summer of 2012. She said the young woman graduated from high school last year and was in a local production of "Sunset Boulevard."
"She was a very talented actress and singer," said Mallory. "She's a lovely, lovely girl. Very sweet, kind."
In April 2014, a Facebook post under Emily Janzen's name said she had just been accepted into the University of British Columbia's opera performance program. Late last month, she tweeted how thankful she was to be alive.
"Whenever I start to feel sorry for myself, I just thank God I'm still alive. I complain about all the pain, but at least I'm here to feel it."
Last October, she posted a photo of herself on Facebook.
"Emily you are awesome," her father commented.
"Love ya daddio," she responded.
— With files from Tamsyn Burgmann and Clare ClancySuggest a correction