The blaze broke out in the science block of the school in Kalinda Road, Ringwood, about 7.10.

More than 100 firefighters from the Metropolitan Fire Brigade and the CFA fought the fire for nearly two hours to contain it just after 10.

MFB assistant chief fire officer Greg Bawden said a lack of water pressure and access in and around the science block due to the shape of the site hampered firefighting operations.

‘‘An aggressive attack and rapid intervention by both MFB and CFA crews managed to prevent the fire spreading to a nearby library and computer wing,’’ he said.

Two firefighters suffered minor injuries; paramedics treated them at the scene.

Ambulance Victoria spokesman Paul Bentley said one of the patients, a 52-year-old man, suffered a leg injury and was taken to Maroondah Hospital in a stable condition.

Senior students were due to return to school today for a preparation day, before the rest of the school returned on Thursday for the start of the school year.

The school will be closed for the rest of the week and re-open on Monday.

MFB firefighters remained at the school overnight to ensure the ruins of the building did not ignite again.

The cause of the fire is still being investigated.