Firefighters were called to a burning building in East Grinstead on Thursday afternoon (October 31).
At 5.08pm, crews from Crawley, Forest Row, Uckfield and Godstone attended the property in Maypole Road.
On arrival, firefighters found fire and smoke coming out of the building’s ground floor.
A spokesman for the fire service: “We forced entry through the site hoardings and were told there were 3 youths seen inside.”
East Grinstead Fire said two firefighters made entry in breathing apparatus with a hose reel and fog nail.
They later said eight firefighters in breathing apparatus were used to search the property and extinguish the fire.
The incident is currently under investigation.
A spokesman for West Sussex Fire said: “We received a call at 5.05pm to a report of a fire at Maypole Road, East Grinstead.
“Two appliances were initially sent from East Grinstead and Crawley.
“Upon arrival crews encountered a fire in a large three-storey derelict house and a further four appliances were requested. Eight breathing apparatus, one fog nail, three hose reels and safety jets were used.”
Crews left the scene at 7.35pm.