Firefighters were called to a two-apartment home on Cabot Street in downtown St. John’s shortly before 3 a.m. Sunday.

Residents on the main floor heard a loud bang and smelled smoke. They called 911 believing there was a chimney fire.

When firefighters arrived on the scene they found a fire in the apartment at the rear of the century-old home. They upgraded the call from a chimney fire to a structure fire.

Firefighters found a man inside with the help of a thermal imaging camera. He was quickly removed and rushed to hospital in critical condition.

Firefighters were quickly able to knock down the fire, limiting damage to the apartment, but there was some smoke damage to the main floor. The occupants of the main floor were able to escape uninjured.

At this point the fire appears to be accidental in nature and not suspicious.