Firefighters battled through the night after a building was deliberately set alight in Hastings.
Three crews were called to The Ridge after police spotted smoke coming out of a two-storey building last night.
The fire service said on arrival firefighters discovered the blaze had been started in a ground floor electrical cupboard of the 75m by 50m derelict building.
Firefighters from The Ridge, Broad Oak and Bohemia Road attended and fought the flames using two hose reel jets. UK Power network engineers were also called and isolated the power.
The fire has since been extinguished and investigations have discovered it was started deliberately, the fire service added.