POLICE believe an electrical fault caused the fire at the Sigatoka Methodist Primary School early on Monday morning.
Police spokeswoman Ana Naisoro said their investigators had checked the sub meter box in the school premises as part of the investigation.
"And at this initial stage, we believe the fire that destroyed part of the school could have been as a result of an electrical fault," Ms Naisoro said.
Damage is estimated at more than $500,000.
Thirteen classrooms, the headteacher's quarters and the multi-purpose hall were destroyed in the incident.
Meanwhile, concerns have been raised by the police on the alarming increase in structural fires in the West.
Two fires were recorded at separate locations in Ba within a 48-hour period this week.
Ms Naisoro said in the first incident, a 65-year- old farmer lost his two-bedroom corrugated and timber house about 10am.
"The house was occupied by two canecutters but was vacant at the time of incident," she said.
"The cost of damage is estimated at $6000 although the cause of fire is unknown as investigations continue."
As well, a bure belonging to a 66-year-old farmer of Koronubu was destroyed at 9:40pm.
The cause of blaze is yet to be determined.