A house fire on an island in Newfoundland's Conception Bay has claimed the life of a five-year-old boy, his seven-year-old sister and their five-year-old male cousin.

RCMP said the fire destroyed a two-storey home in Lance Cove, a town on Bell Island about 35 kilometres west of St. John's, N.L.

By the time fire crews got to the scene at about 3:30 a.m. Saturday, flames had engulfed the entire structure, police said.

"It seems like it went up pretty fast," said RCMP Cpl. Trevor O'Keefe. "It was an old two-storey wood home, so I guess once that catches, it can move pretty fast."

Two children and three adults managed to get out and were taken to hospital.

O'Keefe said that none of the injured suffered life-threatening injuries.

"The kids that died in the fire, it was a brother and a sister and their cousin," said O'Keefe. Police haven't released the names of the victims.

Gary Gosine, mayor of the nearby town of Wabana, N.L., said he's been told the survivors "are going to be okay," The Canadian Press reported.

But the tragedy has shaken the small community.

"There's no question this is completely devastating ... just before Christmas with family and kids involved," Gosine said.

"It doesn't matter whether it's June or December, but somehow when it's around Christmas time and everybody is supposed to be enjoying themselves ... especially kids waiting for Santa, it's tough," he said.

Investigators are still trying to determine what caused the fire.

"Once everything cools down on the scene, then we can start sifting through the evidence ... But it's hard to say how long it will take before we come up with a cause," said O'Keefe.

With files from The Canadian Press