A smoke alarm helped save a woman's life early this morning in Cedarbrae, the Calgary fire department says.

A neighbour spotted the flames in the 100-block of Cedardale Crescent southwest around 1 a.m.

When firefighters arrived, a significant portion of the exterior of the townhouse was on fire, but it was brought under control quickly.

The resident and her dog had already got out safely by the time fire crews arrived.

"This fire demonstrates the vital importance of having working smoke alarms installed in your home as the smoke alarm activation played a critical role in alerting this resident to the danger," the fire department said in a release.

There was little damage to the inside of the residence.