Police are investigating the circumstances surrounding a suspicious fire overnight at a school in Galston.
About 1am today (Monday 19 May 2014), emergency services were alerted by neighbours to a fire in the grounds of a school on Galston Road.
Fire and Rescue NSW attended a short time later and found the multi-storey library block well alight. The roof of the building had already collapsed.
Police from Kuring Gai Local Area Command also attended and have established a crime scene.
Investigators are treating the fire as suspicious and a police guard remains at the school.
Later today crime scene and fire investigators will examine the library when it is safe to enter the building.
It is estimated that the repair bill for the building and to replace its contents will be in excess of $2 million.
Police have urged anyone with information about suspicious or unusual activity near the school overnight to come forward.