A fast-moving fire destroyed a family home in Rocky Harbour Friday morning. (CBC)

A family in western Newfoundland is citing good timing and their son's instincts with saving their lives early Friday, a police officer said.

The man, 19, came to the family's home in Rocky Harbour at about 2:30 a.m., and immediately smelled smoke coming from the basement.

"He banged on the walls to wake up people in the house," said Const. Annick Lafleur, who works with the RCMP detachment in Rocky Harbour, a popular tourist town in Gros Morne National Park.

"When he went into the basement, he said, 'I couldn't see the furnace. It was just like a big ball of fire,' " she said.

His parents and his older brother had been sleeping upstairs. They were not awoken by an electrical fire alarm system in the house.

"The younger son was out with some friends and came home for something to eat," she said. "He woke up his mom and dad and his older brother and got everybody outside and said, 'We have to go out, the house is on fire.' "

Lafleur said the results could have been tragic had the son not arrived home when he did.

"[The parents said] probably if their younger son didn't [come] back home, they probably would not wake up," she said.

Lafleur said the fire quickly destroyed the home.