An elderly man is fighting for life after an explosion tore through a retirement home in northern NSW.

Emergency services were called to a single-level retirement unit on Monarch Dr in Kingscliff about 7.30am on Monday.

Paramedics rushed to the home and treated an 85-year-old man with severe burns.

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He was taken to the Royal Brisbane Hospital in a critical condition.

An 83-year-old woman, with minor burns to her face and body, was taken to Tweed Valley Hospital in a stable condition.

Fire and Rescue NSW (FRNSW) said they are investigating whether the fire, which completely destroyed the home, was caused by a leaking LPG system.

It took four FRNSW trucks and 14 firefighters to bring the blaze under control, with firefighters managing to stop the fire from spreading to adjoining homes.

Police said they are working with FRNSW to investigate the cause of the explosion, however, they said initial advice to police indicates the cause may be a leak from an internal portable gas appliance.