Fire damage was so extensive to a one-story warehouse at the old Waialua Sugar Mill that Honolulu Fire Department investigators were unable to determine the cause of the blaze, HFD announced Monday.

But the estimated $1.2 million in damage at the old Waialua Sugar Mill property was confined to the building and contents that housed a wood mill, not the 5,000-square-foot warehouse where tourists have been able to return to shop for coffee, shave ice and other products.

“It’s a real tragedy for the guys; they lost everything,” said Bill Martin, owner of Island X Hawaii, who sells a variety of local food items including Hawaii-grown coffee and cacao products, which are processed on-site at the former sugar mill. “We were not affected. Tour companies were calling to make sure we were not affected.”

Damage to the building was estimated at $1,012,500, and its contents at $180,000, the Fire Department said.

Woodworker Chris Bruns says on his Facebook page that he did not have insurance for the contents of his wood shop. But he had brought home a koa chest he finished Dec. 24 and said, “It would help me out a lot to find a buyer for (it).”

Bruns specializes in fine woodworking, including custom furniture, cabinetry, stairways and doors.

“Dan Moore’s and my shop burned up today,” he posted on Facebook. “All humans and dogs are safe. Have no idea what started it. Thank you to all the firemen putting their lives on the line. Thank you also to all concerned.”

Hawaiian Lumber is owned by Dan Moore, a big-wave rider and cabinetmaker. Moore was on his way to Switzerland for a vacation when he learned of the fire, Martin said.

Hawaiian Lumber’s website says Moore was running a thriving cabinet shop and surfboard business but bought two large wood mills in order to mill exotic reclaimed trees, and stocked live edge slabs and did custom milling.

Bruns and Moore could not be reached Monday.