An investigation is still ongoing into the fire at the former Moira House school in Eastbourne.
Emergency crews were called to the disused building on Upper Carlisle Road just before six last Sunday evening.
Police believe the fire was started deliberately.
Detective Sergeant Tod Stewart said: “We are continuing to pursue lines of enquiry, and are appealing for anyone with information to come forward.
“We are also keen to trace four boys as witnesses, who may have information to help our investigation.”
Information relating to the fire can be reported to Sussex Police online, quoting serial 936 of 19/10.

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