Sussex Police can confirm that the fire at Millais School on Thursday, March 20, is now being treated as a crime.
This follows an extensive examination of the scene by both Sussex Police and West Sussex Fire and Rescue Service that suggests that the fire was started either deliberately or recklessly.
The effective smoke alarm system and efficient emergency evacuation procedure meant that students and staff were able to leave the building quickly, without panic or injury, after the fire was discovered.
A comprehensive criminal investigation is now underway to identify both the exact cause of the fire and those responsible.
Officers, supported by fire service staff, are working closely with Millais School to ensure that this investigation can be progressed effectively whilst minimising the continued disruption to the pupils, staff and daily functioning of the school.
It is likely that there will be a police presence at the school for a number of days as this investigation progresses and we are keen to hear from anyone that may have information.
If you know anything at all please call 101 quoting Operation Broadband or the independent charity Crimestoppers anonymously on 0800 555111.