A massive fire at a home under construction in Lawrence Park has been put out after burning for more than 12 hours but officials say that they are still working to extinguish some hotspots.

The fire began in the basement of the unoccupied home located on Rochester Avenue near Lawrence and Bayview avenues at around 7 p.m. Thursday.

Division Commander Bob O'Halloran told CP24 on Friday morning that crews initially tried to battle the fire from inside the 5,000 square foot structure but had to retreat to a defensive position when the floors were compromised and “stuff started falling down around them.”

At one point, the call was upgraded to a six-alarm response to accommodate the need to frequently rotate out crews amid the extreme cold.

As of 11 a.m. on Friday, the blaze was considered to be out but a significant number of firefighters did remain on scene.

“There are some hotspots that flare up from time to time. We are trying to deal with those but we are having difficulty because of the fact that we can’t really put people inside,” O'Halloran told CP24. “The floors are gone and some of the material from the floors and the other parts of the structure that collapsed created void spaces and the fire is burning in them. We are getting at it as best as we can.”

O'Halloran said that crews were able to keep the fire from spreading to neighbouring homes, though one residence next door did end up with some basement flooding as a result of the significant of water runoff as crews battled the blaze.

He said that Toronto Fire Services investigators are on scene but may have a hard time determining the cause of the blaze due to the sheer scale of damage.

“Hopefully they will be able to but with a lot of damage like this it is going to be difficult,” he said.

In an update on Friday afternoon, Toronto Fire Chief Matthew Pegg said crews are trying to determine whether they will need heavy equipment to dismantle the home to allow crews and investigators to get inside.

“Our incident commanders that are here will make that determination over the next few hours. It will either be our crews doing that just methodically or we will engage heavy equipment,” Pegg said. “Either way there is a significant amount of work ahead.”

Pegg said there is no evidence to suggest that the fire is suspicious at this time.

“It is really hard to forecast or guess at this point as to whether or not they will be able to get a conclusive cause. We know the home was under extensive renovation,” he said.

“I need to let operations crews finish all of the suppression. We’ll turn it over to investigations and they can do their work but there is an extensive amount of damage so they have a tough road ahead of them.”

Mayor John Tory spoke to reporters at the scene of the fire on Friday and thanked firefighters and city staff for keeping the six-alarm blaze under control.

“Thank goodness that nobody was injured and that really to the maximum extent possible, property was preserved,” Tory said.