A man is unaccounted for hours after a three-alarm fire tore through his North York home early Thursday morning.

Fire crews were called to a home at 28 Camwood Cres., near the DVP and York Mills Road, shortly before 7 a.m. Officials estimated that the fire probably started around 4 a.m., but wasn't reported for several hours.

When they arrived, they found the brick home engulfed in flames, Toronto Fire Capt. Mike Strapko said. Eighteen fire trucks and 80 firefighters were called in to help get the "stubborn" fire under control.

One of the firefighters had to be transported to hospital with burns to his forehead, but Strapko said the injuries are minor.

A 68-year-old man, believed to have lived alone in the house, has not been located. It is not known whether he was home when the fire started. Division Commander Andrew Kostiuk said the man suffers from dementia. Police are canvassing the area, searching for signs of the senior.

Firefighters were unable to enter the home to conduct a search early Thursday morning, because the fire spread to the walls and attic, making the structure unstable. The first floor collapsed into the basement during the fire. 

The fire is being treated as suspicious until its origin is confirmed. The fire caused an estimated $300,000 in damage.