Investigators now say they are looking into whether the blazes are related to another fire in the same area a few weeks ago.
Crews responded to the first overnight blaze, at Olga Artworks, just after 3 a.m. after receiving a 911 call about smoke in the area. When they arrived, firefighters found the ivy-covered building on fire and called in a full response.
As crews were extinguishing that blaze, another 911 call came in at about 3:30 a.m. reporting a fire at a home on Willis Lane, about three miles away. As available crews responded to the second fire, they found flames and smoke pouring from the building.
Additional crews eventually were called in from San Juan Island and Lopez Island fire departments to help mop up the blazes.
At noon, firefighters were still dealing with some hot spots in the roof of Olga Artworks, which displays and sells work by local artists, including paintings, pottery, prints, sculpture, jewelry and glass.
There were no reported injuries in either blaze. A damage estimate was not immediately available.
Both scenes are under investigation by the San Juan County Fire Marshal's Office.