Three families have been displaced and one man is in hospital with serious burns following an early Saturday morning double-house fire in Cumberland.

Crews responded to a fully-involved structure fire at 5:40 a.m. along Dunsmuir Avenue in an area also known as "camp road".

When they arrived, crews found a first home was fully engulfed and flames were spreading to the eastern wall of a second home that was occupied by two families, according to deputy chief Craig Windley.

"A lot of these houses are close to 100 years old, they were old mining houses back in the day so a lot of these houses are still filled with coal dust, cedar inside and outside with cedar shakes" Windley says.

One man from the first home was airlifted to hospital in Victoria with significant burns. A neighbour tells CTV News the man believed one of his children was still inside the home and went back in to try to get them out.

A woman living downstairs in the adjoining home that was damaged heard some noise and that's what alerted her to the fire. She said there was also someone banging at the front door to warn them about the danger. The occupants of that home escaped unharmed, along with several pets.

Determining a cause of the fire may prove to be a challenge for investigators because of the extensive damage. Windley believes the first house will have to be knocked down and rebuilt, while the second is salvageable.

The heat of the blaze also partially melted portions of two vehicles parked outside the buildings.

Upwards of 13 people are believed to now be displaced because of the fire and Emergency Social Services representatives were on scene providing assistance.