East Sussex Fire and Rescue Service says nobody was injured in the fire in Lenham Avenue, Saltdean.
Two fire engines and two four-by-four vehicles were sent to the scene in Pevensey.
The fire is ruled an accident by East Sussex Fire and Rescue Service.
Fire services in Sussex, Surrey and Kent have all issued advice on how to help with prevention.
Steven Conisbee, from Fetcham, says the speed at which flames engulfed his land was "alarming".
Several fire engines are at the abandoned College Of The Holy Child Jesus on Magdalen Road.
Mary Joy Langdon recalls joining the fire service in 1976 in Battle and the ensuing media interest.
Six blazes caused by strikes have been dealt with by crews across Kent, East Sussex and West Sussex.
Several fire engines are pictured responding to the incident in Nevill Road, Hove.
