Two Big Island cabins at the historic Quonset hut were damaged Friday.
The fires were reported around 1 a.m. at the Humu'ula Sheep Station cabins where Saddle Road meets Mauna Kea Access Road.
The fires were not put out until almost 5 a.m.
No reports of injuries.
According to several online reports, the site was used as part of a thriving sheep industry from the late 1800s to the early 1960s.