The building was under construction and an extension cord wore down and caused the fire.
The blaze broke out about 4:25 a.m. Friday, in the pool house of the Sugar Loaf Conference Center along the 9200 block of Germantown Avenue.
When firefighters arrived flames were spitting out of the first and second floors.
Everyone managed to get out safely.
L&I was called to the scene to determine if any structural damage was done.
There were no reported injuries.