The Monday afternoon fire that caused an estimated $110,000 to the Diamond Head home of “Hawaii Five-0” star Alex O’Loughlin was ruled accidental.

Fire Capt. Terry Seelig said Wednesday the cause was spontaneous combustion from oily rags used in a woodworking project that had been left in the garage.

The fire on Makalei Place gutted the garage and destroyed its contents.

Seelig said this type of fire occurs several times a year where oily rags are left piled up or thrown in the trash and begin to smolder and burn. It also occurs at hotels where cooking oils that remain in rags that have been laundered and put in the dryer also can catch fire due to spontaneous combustion, he said.

Seelig recommended placing oily rags for disposal in a metal container with a lid, such as a metal trash can and not a plastic can.