About 2:20 p.m., a passer-by called in a fire at the home of James and Julia Paschal on Lake Shore Drive in Martinez. The couple were not home at the time.
Their son, Battalion Chief Jimmy Paschal, supervised the effort to extinguish the blaze.
"It started in the area of the HVAC under the house," Paschal said of the fire that firefighters had to crawl under the brick home and cut holes in the floor to put out. The fire was contained to below the house and in the wall cavities.
"It appears accidental," Martinez-Columbia Fire Investigator Capt. Daniel Gwinn said.
Gwinn said the state Fire Marshal's Office was called in as protocol when a fire occurs at the home of a firefighter or his family.