The children's mother was not home at the time of the New Year's Day fire.
RCMP Cpl. Dan Moskaluk said a preliminary investigation suggests the blaze was not suspicious.
"The Sicamous RCMP and Victim Services personnel continue to assist the family of the deceased and have expressed our deepest condolences to them for their terrible loss," he said.
Fire chief Brett Ogino said the home was fully engulfed when firefighters arrived at about 6:30 p.m.
Mayor Darrell Trouton said the community of 3,000 people is reeling from the triple tragedy.
"It's just sad and it makes you sick to your stomach," he said.
"We're working with the fire department and looking into critical stress debriefing for them as well."
The deaths occurred three days after newlywed firefighter Dan Botkin died in an explosion at a log home building company in the neighbouring community of Enderby.
No names have been released in connection with Sunday's fire, and Moskaluk said the family has asked for privacy.