Fire officials are urging residents to check their smoke detectors after a blaze tore through a Brampton home on Monday morning, killing three young children and their parents.

The fire began in a home on Conestoga Drive just before 2 a.m. Monday.

It was so ferocious that firefighters had to retreat at first before attempting rescues of those inside.

They pulled four people out but all four succumbed to their injuries in hospital. A fifth person was found dead inside.

Family posting on social media and crowdfunding websites identified the parents as Nazir Ali and Raven Ali O’Dea, and their three children as Alia, 10, Jayden, 8 and Layla, 7.

The children’s maternal grandmother also suffered severe burns and remains in hospital in critical condition. Two tenants living in the home's basement managed to escape uninjured.

At this point the cause of the fire remains unclear, however the children’ grandfather told CTV News Toronto on Monday that he believes the home did not have working smoke detectors.

Speaking with reporters at the scene on Tuesday, Ontario Fire Marshal John Pegg said that while investigators are still trying to determine whether that is in fact the case the absence of working smoke detectors could provide an explanation for the tragic outcome.

“Fire spreads so fast in our houses nowadays with the construction that we have and the plastics that are in there, so the smoke is so thick and black (as a result),” he said. “If you don't have a working smoke alarm, unfortunately we are going to see more tragedies like over my shoulder. We need to get serious. We need to be serious about smoke alarms.”

At the charred remains of the home on Tuesday, fire investigators in coveralls were seen coming in and out of the structure.

Pegg said that investigators will likely remain on site for at least one more day as they continue to work to determine the cause and origin of the fire.

In the meantime, he said that he wants to remind residents of the importance of ensuring that they have working smoke detectors.

He said that in addition to being required by law ”a simple battery-powered smoke alarm that can cost you $10 to $15 can save the life of you and your family.”

“Hypothetically, I can say that if you had a fire that started in an area of your home it burns so fast and so black, if that smoke alarm goes off even if you're in the other end of the house you'll hear that alarm and you have the chance to get outside,” he said. “But on the flipside, if you don’t have working smoke alarms that fire will spread throughout the house and potentially block your exit and you will be in a situation where you are in thick, incredible smoke and you can’t see. It really is a difference maker.”

Brampton fire

Grief councillors made available by Peel school board

The three children who perished in the fire all attended school within the Peel District School Board.

The board has not said which school the children attended but has indicated that grief councillors and other support staff from its Critical Incident Response Team will be available to assist students and staff for as long as they need it.

Meanwhile, Brampton Fire Chief Bill Boyes told reporters on Tuesday that the firefighters who were at the scene on Monday are “heartbroken” and are “mourning” along with the entire city.

The children’s aunt also took a moment to remember her nieces and nephew during Tuesday’s press conference, telling reporters that they were the kinds of kids “who really loved who they were and not what they had.”

“I think that is a really beautiful quality and I just can’t believe I won’t see them again,” Bismah Ali said.

Police kept Conestoga Drive closed again on Tuesday to allow investigators room to maneuver.