A simple smoke alarm has saved the lives of a family of four in a Ti Tree Resort unit in Port Douglas last Thursday morning.

An electrical fire began in the bedroom near the air conditioner, but the entire unit stood blackened as smoke damage took its toll on other rooms before local Queensland Fire and Rescue Service members extinguished the blaze.

Temperatures within the burning unit were hot enough to blast windows outwards, but fast action from the QFRS, and the solid cement block structure of the building prevented the fire spreading into neighbouring units.

"When we arrived it was well engulfed with fire coming through the bedroom," QFRS Port Douglas Auxiliary Captain Lou Leone said.

Neighbours were evacuated but were later allowed to return, however Mr Leone said the residents "won't be able to use the unit for quite some time."

Mr Leone said the effectiveness of the smoke detector was a timely reminder for everyone to ensure they are equally as prepared.

"They were asleep, and the smoke detector did the job and woke up the occupants so that was a good thing."