The flames towered over Robert E. Lee Elementary School on E. Columus Drive in Tampa Tuesday night.
At one point, firefighters pulled back, fearing the 111-year-old school's roof would collapse during the three-alarm fire.
Now that the fire is out, Tampa Fire Marshal John Reed says investigators aren't focusing on arson, but electrical issues.
The school had been without power because of Hurricane Irma, bu the the power was restored a short time before the fire erupted.
Damage has been estimated at nearly $5 million. The school district says there are plans to keep Lee Elementary students together at another location when class resumes on Monday.