The exterior walls still stand.

But that’s about all that remains after a fast-moving fire tore through the roof and rear walls of a Friday Harbor home, and gutted much of its interior, early Tuesday afternoon.

For Rhonda Johnson, who rescued her home from the brink of foreclosure several years ago, the fire proved a devastating turn of events. She was running errands and not at home when the fire was first reported.

“I worked my a– off for that house,” Johnson said, as firefighters combated hot-spots lingering on the smoldering home. “I guess it hasn’t really hit me yet. I just thank God no one was home and that it didn’t happen at night when all of us would’ve been sleeping.”

Sheriff Bill Cumming was among the public safety personnel first on the scene. Smoke was pouring out the windows and the interior was already ablaze, Cumming said.

“We forced open the front door and yelled inside to make sure no one was in there,” he said. “We removed a motorcycle from the garage, and were able to throw a small propane barbecue off the back porch, but it was so hot we had to just back away.”

Cumming said residents of the Argyle Avenue home — five in all — were each accounted for, and safe, shortly after the fire, which broke out at about 1:30 p.m., was first reported. Johnson, mother of two, rented the ground floor of the home to a friend, mother of a young child as well.

A billowing column of black smoke could be seen towering above the two-story structure, located just one lot north of the fairgrounds, for miles.

Firefighters from the Town of Friday Harbor and San Juan Island Fire Department were on scene within minutes of the initial page, which went out at 1:48 p.m. Chief Steve Marler of San Juan Island Fire Department said the fire proved difficult to battle and to contain because of the extensive amount of remodeling that had been done to turn a modular home into a two-story structure.

“The difficulty with this particular fire was the building was basically a structure within a structure,” Marler said. “There were a lot of little void spaces where the fire could refuel itself, and I think we ran into just about every type of building material there is inside there.”

Once it was determined to be unoccupied, Marler said firefighters refrained from going inside the house because its roof was on the verge of collapse and the stability of the first floor was questionable. The fire was knocked down and contained about one hour after the first wave of firefighters arrived on scene.

Marler said some belongings in the ground floor of the home may have been spared, and that contents of the garage are relatively unscathed.

“That’s the one area that the fire didn’t breach,” he said.

The cause of the fire remains under investigation, led by Friday Harbor Fire Chief Vern Long.