A fire at a derelict property is believed to be arson.
The building in Bolnore Road, Haywards Heath was torched yesterday afternoon.
Firefighters from West Sussex Fire and Rescue Service (WSFRS) tackled the blaze for hours.
A spokeswoman for WSFRS said: “Yesterday, September 20, we were called at 3.31pm to a fire involving a derelict property Bolnore Road, Haywards Heath.
“Joint fire control mobilised seven fire engines from Haywards Heath, Burgess Hill, Crawley, Worthing and East Grinstead as well as crews from East Sussex Fire and Rescue Service to the scene.
“Firefighters wearing breathing apparatus tackled multiple fires that spread over three floors at the derelict property.
"A fire investigation has been completed and the fire is believed to be of deliberate ignition."
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Bolnore Road is home to several derelict houses and is just a stone’s throw away from a former care home in Bolnore Farm Lane which went up in flames in November last year.
A spokesman for Sussex Police said: "Officers are appealing for witnesses following a reported arson in Haywards Heath.
"Emergency services were called to a derelict building which was on fire on Bolnore Road around 3.50pm.
"The incident, which is believed to have been a deliberate ignition, is being investigated.
"If you saw anything suspicious, or have any relevant footage, please report online or call 101 quoting serial 006 of 20/09."