When firefighters arrived at Faylane Elementary School around 8 a.m. Saturday morning smoke was coming out of a corner room.
Crews managed to knock the flames down in minutes. Firefighters said the blaze was caused by an electrical problem.
"The fire actually smoldered in that room for about five to eight hours before it was actually detected," said Garden Grove Fire Department Battalion Chief Nick Booker.
The fire was confined to the school's library which had just been renovated on Friday.
"It's so ironic," said 2nd-grade teacher Cindee Heigis. "How could we be here yesterday doing a makeover and it completely burned and devastated the next day? It's just hard to fathom."
Dozens of volunteers from the non-profit group, "Give and Grow Foundation" gathered at the school Friday to give the aging building and grounds an extreme makeover.
They painted murals on walls, constructed a new kindergarten play area and installed new softball diamonds.
Heigis says seeing the damage caused by the fire after so much hard work, is surreal.
"We had so many people here. They were all upbeat, just giving of themselves, cleaning up our school and making it a happy place," said Heigis.
As discouraging as the fire is, volunteers are already looking ahead. They plan to go back to work and get the library fixed up and ready for the students when classes start on September 10.