Firefighters responded at about 9:30 a.m. Wednesday morning to a single-alarm structure fire at a building on Crescent Bay Drive in Lake Forest.
Firefighters were able to contain the blaze, which started when a panel in an electrical room melted, from spreading, fire officials said.
Heavy black smoke poured from the room before the fire was quickly extinguished.
Shortly after 10 a.m., employees of area businesses stood outside the building where the fire occured while firefighters and employees with Southern California Edison dealt with the aftermath.
Edison employees were on scene because the blaze was electrical, Capt. Marc Stone with the Orange County Fire Authority said.
No injuries were reported.