MODESTO, Calif. - A massive four-alarm fire that ripped through a California millwork plant in June was caused by arson, investigators have ruled.

American Lumber Co. suffered around $2 million in damage to its facility and inventory on June 18. The fire destroyed four buildings that were no longer in use, but also a fully functional mill, forklifts, and other materials, reports the Modesto Bee.

The company was able to reopen two weeks after the fire.

And now, after a two-month-long investigation, the Stanislaus Fire Investigation Unit believes it was caused by arson.

Investigators didn't say much else, like whether or not an accelerant was used or if any suspects have been identified.

American Lumber Co. is a century-old, family-owned manufacturer of custom millwork, windows, doors, building materials, and hardware.