One person has been taken to hospital following a large fire in Mississauga overnight.

The two-alarm fire broke out around 1 a.m. on Tuesday at a house at 5132 Forest Hill Dr., which is north of Eglinton Avenue West and west of Mississauga Road.

Speaking to the media at the scene, Chief Deryn Rizzi, of Mississauga Fire and Emergency Services, said that the occupants of the home self-evacuated “due to high heat conditions” and called 911.

She said firefighters at the scene encountered “black smoke from floor to ceiling” when they opened the front door of the house along with a “deep seated fire.”

Three crews then entered the dwelling, she said, two of which remained on the main floor and the third proceeded to the second level where they were met with “absolutely high heat conditions, blacked out conditions.”

“They could not see anything” she said, adding the fire also caused one of the stairwells in the house to be “burned out completely,” said Rizzi, who also serves as Mississauga’s director of emergency services.

“The conditions upstairs just with the heat, the flames the smoke, it was untenable.”

Rizzi said the weight of the home’s clay roof was especially concerning for those battling the fire as it had made its way into the attic.

“We toned out an alert, which pulled our firefighters out. We changed our strategy from an offensive, fighting the fire from the inside, to a defensive attack,” she said, adding crews continue to be on the lookout for any hotspots and are still working to determine the main point of the fire.

Peel paramedics transported one patient, an occupant of the house, to the hospital.

A neighbour was also assessed at the scene for smoke-related “medical conditions" and released.

Robert Monardo told CP24 that shortly after 1 a.m. he heard an alarm coming from his neighbour’s house and saw a large cloud of thick smoke coming from the residence when he looked outside. Monardo said he called 911 right away and about seven minutes later firefighters and police were at the scene.

As a precautionary measure, residents of neighbouring homes were evacuated, he said.

The “root cause” of the fire is now under investigation, Rizzi said.

A fire prevention investigator has been called to the scene.