The fire began about 5:31 a.m. at a single-story structure near the intersection of Kyle and Catalina streets, according to the Orange County Fire Authority.
Firefighters arrived at the scene and initially took up defensive positions as flames emitted from the roof of the building.
No injuries were immediately reported.
A spokesperson for the Fire Authority said that challenges involved in the firefight included hazardous materials inside the building and electrical wires overhead.
Video from AIR7 HD showed hoses dumping water on the blaze from several aerial ladders.
Although the Los Alamitos Unified School District offices are located nearby, they were not exposed to the flames, the OCFA spokesperson said.
The cause of the fire is under investigation.