The fire broke out at a home on Miller Road in Oakville near Trafalgar Road and the Queen Elizabeth Way.
Firefighters got to the home within minutes of being called. When they got there, the roof and first floor of the home were already ablaze.
Fortunately, the people inside the home made it out unscathed.
Vera McManus said smoke detectors woke her teenage grandson.
"The fire alarm was going haywire and the boy woke up and he got his mom," McManus told CBC News.
Her grandson’s father and little brother were away when the fire broke out.
The fire is believed to have started on the back deck and spread to the house.
The cause of the fire is under investigation.