None of the people living in the property, or the one above, were injured in the fire.
The passer-by alerted firefighters at around 21:49 and two fire engines – one from the Western station and one from the Fire Service headquarter – were sent to the property, located at the bottom of Beaumont Hill.
When the 10 firefighters from Red Watch and the Duty Manager arrived, they could see flames through a ground floor window, while a “well-established” fire was starting to engulf a ground floor room.
Two firefighters equipped with breathing equipment went inside and put out the blaze.
Another team then checked the property above to ensure no one was in the building and confirm the fire was confined to the ground floor.
The residents from both properties were checked by paramedics and were luckily uninjured, although shocked by the incident.
Watch Commander Mark Bailey-Walker from Red Watch commended the islander who gave the alert.
“The quick actions by a passer-by in calling the Fire and Rescue Service immediately ensured that this fire, although serious, didn’t escalate into a fully involved house fire,” he said.
“Their call definitely made a difference to the outcome of this incident.”
Police are now investigating the cause of the fire.
Pictured top: The fire damage at the property. (JFRS)