Eight people had to be evacuated from their homes in St Ouen overnight following an explosion and fire in an oil heating system.
Fire crews were called out just before 1.30am.
Two engines were initially dispatched.
They found the fire had spread within the roof of the nine properties. A third appliance was sent to the scene.
14 firefighters attended and used breathing apparatus and high pressure hose reels to put out the blaze, understood to be in sheltered housing.
The residents were evacuated because of the large amount of smoke. Two people were taken to hospital for smoke inhalation.