Police are appealing for information after a suspicious fire broke out at Mount Annan High School last night.
Police were called to the school on Welling Drive, Mount Annan at 1.30am this morning following reports of a fire.
Fire and Rescue NSW attended and extinguished the blaze which caused significant damage to the library of the school.
There were no injuries as a result of the fire.
Camden Police Area Command police officers established a crime scene and have begun investigation into the matter.
This follows a fire that broke out in the school's science block last month.
Fire and Rescue NSW Narellan said on its Facebook page at the time that "early intervention by NSW Police Force assisted [them] in locating the fire quickly."
"Crews gained entry and rapidly attacked the seat of the fire using high pressure hose lines," the post said.
"The fire was contained to the room of origin and the area given an all clear from HAZMAT technicians from Fire and Rescue NSW Rosemeadow."
The classroom sustained a substantial amount of smoke damage to the walls and furniture.
A blunt object was used to damage 12 windows to the science block of the school.
Police believe the fire was deliberately lit.
The cause of the fire is still under investigation.