The boy was one of seven people — a woman, her sister and five of the woman's children — inside the building as it went up in flames early Saturday morning, but he was the only one unable to escape.
He was brought out of the burning building in cardiac arrest and rushed to BC Children's Hospital in Vancouver where he died Sunday.
It's not clear exactly when the blaze broke out or when the six other people in the house escaped, but police officers driving by on routine patrol spotted the fire shortly after 3 a.m. PT.
Witnesses say RCMP made several attempts to get into the building, but were driven back by the heavy heat and smoke. The fire department arrived about four minutes later as flames poured from the upstairs windows.
"Our crews made some really brave attempts to knock back the flames while doing a search of the building, of the top floor, and found the child in the back bedroom," said Martin Drakeley, the assistant chief of the Nanaimo Fire Department.
Drakeley said the boy was in cardiac arrest when he was brought out of the building, but was stabilized by paramedics.
He was initially taken to Nanaimo Regional Hospital, where he was then transferred to BC Children's Hospital in Vancouver. Weather conditions wouldn't permit the use of the air ambulance so he was taken to the Vancouver hospital by hovercraft.
The cause of the fire has not been determined.