A garda on the beat on John Street at 9.30am this morning spotted smoke coming from a historic building and entered the building and rescued a sleeping couple.
The male and female who were asleep in the burning building were not injured.
Gardaí have launched a criminal investigation and are describing it as 'critical incident'.
The scene has been preserved and emergency services remain at the building.
Five units of Kilkenny Fire Brigade attended the incident.
The unused building was the subject of a preservation order.
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