A call was put in to the Guernsey Fire & Rescue Service at 19:02, reporting the incident.
A spokesperson for the Fire Service said the fire was in the flat’s kitchen, located on the top floor of the building, and had trapped the occupants. He added that the team used breathing appliances to help the residents.
Two Fire Engines attended the scene, blocking the road while the fire was dealt with, but they had returned to the station by 20:30.
One of the occupants was treated for smoke inhalation, but now they are said to all be in healthy condition.