Peel District Police said emergency crews were called to a home on Conestoga Drive, near Sutter Avenue, Kennedy Road and Sandalwood Parkway East, at 1:57 p.m.  for fire reports.
Brampton Fire Chief Bill Boyes said the fire eventually reached three alarms and crews were exposed to dense smoke and intense flames on arrival.
Firefighters attempted an “aggressive internal attack”, but were initially forced to return, but eventually entered the house when it was safe.
The crews managed to get four people out of the house, but later it was found that all of them were dead.  A fifth victim was found dead inside the house during a search.
The Boyes said they believed the two dead adults were the parents of three children, believed to be six, eight and 11 years old, who also died.
“They are upset, they wanted to do what they could, they risked their lives to go to this fire and get these people out, unfortunately it was a terrible result,” Boyes said of firefighters rescuing the scene.
“What happened here today, to lose three children and two adults, is absolutely tragic.”
Rescuers found a sixth adult victim outside the home, who went out on his own and was rushed to Sunnybrook Hospital for treatment of critical injuries.
Two other people who lived in a basement apartment in the house came out unharmed.
Firefighters continued their internal search for several hours after arriving at the scene for the first time.
The fire in the house raged for several hours and the Fire Department was called to investigate what caused the fire.
Police closed Conestoga Drive between Sandalwood Parkway East and Cranmore Court to make way for firefighters to deal with the blaze.
The Boyes said they would look into the condition of the house’s fire and smoke detectors as part of the investigation.
The city of Brampton announced that it will lower the flags at all municipal facilities at midnight today to mourn the loss.
Prime Minister Doug Ford has expressed his sorrow over the “tragic deaths”.
“I can not imagine the pain felt by family, friends and the community. You will all be in our prayers,” he said in an irrelevant statement in Brampton on Monday.
Prime Minister Justin Trinto, who was with Ford, said his thoughts were with the family and friends of those who died.
“We all think of those affected by this horrific, heartbreaking tragic fire,” he said.
With files from the Canadian Press