The fire, which broke out around 4am, severely damaged about 500 lockers, destroying hundreds of students' books and personal belongings. Cranbourne police revealed the crime investigation unit had identified a prime suspect.

Sergeant John Blackburn, of the Endeavour Hills police, added that officers had received numerous calls from residents the evening before the fire, reporting "multiple explosions" up and down Bemersyde Avenue. .

"We are not sure if they (the explosions) are related," he said.

"There was no obvious evidence or damage, but many residents heard these explosions."