Firefighters are still battling a stubborn blaze at a multimillion-dollar mansion that was under construction in a posh Oakville neighbourhood.

Fire officials say the house, which has an assessed value of $6 million, is a total loss.

The two-alarm blaze at 23 Ennisclare Dr. W., near Morrison Road and Lakeshore Road East, was reported at 5:50 a.m.

Flames and smoke were pouring from the house when firefighters arrived, but no one was inside at the time because the house was not yet not occupied.

Construction workers at the scene say the final touches were being put on the house this week to get it ready for the owner or owners, who were scheduled to move into their dream home in about three weeks.

Fire crews continue to battle the fire as of 11:30 a.m., although Halton Regional Police and fire officials say the blaze is under control and is mostly extinguished. Firefighters are trying to extinguish any lingering hot spots that are still smouldering.

The fire proved to be a stubborn one because the flames were located within the roof, officials tell CP24.

At the fire's peak, footage from Chopper 24 showed the home engulfed in flames as a plume of thick, black smoke drifted into the morning sky.

There are no reports of injuries, police say.

The cause is under investigation, but Oakville fire chief Richard Boyes told CTV Toronto's Tamara Cherry that there is no reason to suspect foul play.